Ruby Forest Petit Gateau

This is an homage to the black forest cake, which was my birthday cake for the first 14 years of my life. The reason why we would eat black forest cake was because we would celebrate my birthday in Taiwan, and the bakery in the Shida district where we would stay/live only made one kind of cake that was big enough to serve my extended Taiwanese family. That being black forest cake. Traditional black forest cake is a chocolate cake with kirscht liquor, cherries, fresh cream, and chocolate shavings. Kirscht is a kind of brandy that is imbued with cherries. For this rendition, I actually did away with the kirscht and cherries, instead focusing on black currant and ruby chocolate. I personally loved drinking these boxed black currant juices as a child, mostly because they tasted very similar to grape juice. The flavor of black currant is kind of like a blackberry meets a grape, with subtle notes of some kind of spice, kind of like carraway seed. I have a lot of nostalgia towards that flavor, even though sadly black currants are not available fresh in the States, meaning your best bet at making this recipe if you are an American is using black currant concentrate. I will be honest, this recipe is not easy. It is super technical, requires a lot of unique equipment and ingredients, including a foaming siphon, CO2 cartridges, two different kinds of silicone molds, ice, agar AND gelatin, black currant concentrate and possibly black currant powder, and ruby chocolate. Needless to say, this recipe is not beginner friendly, so I apologize in advanced if you were clicking on this recipe in hopes that this would be super doable(some of the individual components definitely are, but everything together is not for the everyday home cook!).

So going down the line of what went into this beast of a recipe, we have a black currant and ruby chocolate mousse, a black currant and ruby chocolate glaze, a Nutella-infused chocolate cake, a Nutella micro-cake, a Nutella ganache, a black currant gelee, and a piped ruby chocolate garnish on top. This recipe only makes 4 petit gateau(both the Nutella chocolate cake and the microwave cake makes enough microwave cake for closer to 8 though!), so feel free to double the recipe if you are going through the trouble of purchasing all of the ingredients to make these. Like for me personally, I felt like I put a lot of time in, just for 4 cute little petit gateau, when the reality was had I simply doubled the recipes for the Nutella ganache, black currant gelee, the mousse, and the glaze, I would have been able to easily make 8 of these, at basically no difference in time spent too! There are a LOT of components in this recipe, and you should approach making these as a marathon, not a sprint, as at the minimum, it will take at least a day and a half to make these highly complex petit gateau from start to finish.

Now for what I love about the techniques behind this recipe. The mousse is designed to give you enough to fill 5 to possibly even 6 of the petit gateau molds. The reason for this is two-fold. I did not want any air pockets in the petit gateau themselves, and with any spare mousse, which there will be a decent amount of, we will be melting that back down, with a few extra ingredients, to form the mirror glaze that enrobes the mousse! This guarantees not only no waste on that part, but also that the flavors of the mousse itself are being reinforced by the glaze, which will essentially be an even more concentrated version of it! Black currant and ruby chocolate pair really nicely together, since the tartness in each complement one another perfectly, while the color of each is quite similar to the other, having this vibrant, pink-ish hue. The black currant gelee also adds a more concentrated hit of the black currant flavor, just to guarantee that you don’t miss it at all when tasting this dessert, and also to help better distinguish the black currant notes from the ruby chocolate. I did use a high amount of agar to the concentrate, but that was because the gelee did not set up with 1 tsp of agar, and that was even after I froze the gelee for an entire day. Whereas, once I added in another tsp of agar to the batch, the black currant gelee came together with a decent but still palatable firmness and cut very cleanly.

The Nutella ganache is absolutely delicious, and I was fortunate enough to procure Nutella from Germany – European Nutella just tastes better than American in my opinion, and it’s entirely due to the fact that the dairy in Europe is absolutely delicious! I froze the ganache with the gelee, just to keep those layers nicely pressed together. Also because by using a larger insert for the mousse, you can press out more air bubbles that might have formed in the mold. Speaking of Nutella, there are two different kinds of Nutella cake batter. If you want to be lazy/if you do not own the foaming gun, you can also just take the baked Nutella-chocolate cake, crumble that up, and use that as the garnish instead. I totally get it, since a siphon is already expensive to begin with, and getting the CO2 cartridges to charge it with is just burning through even more money. I do prefer garnishing with the micro-cake(which is short for microwave cake), since it takes little time to actually prepare, being baked in just 1 minute, and that porous texture from being charged with so much CO2 is better for holding a dusting of black currant powder(which if you do not want to purchase that on top of the black currant concentrate, don’t even sweat it, it’s 100% purely for the finishing aesthetic). But again, using just the Nutella-chocolate cake is perfectly understandable too!

If I were to rate the difficulty scale on this recipe out of 10, I would give it a pretty brutal 9.8. It was not the absolute hardest dessert(the Shaymin Nerikiri took me 6 straight hours of active time to make) I have ever made, but it was very challenging, and especially from an equipment side, not everyone can make this recipe. It kind of reminds me of when I opened the Atelier Crenn cookbook, hoping to recreate chef Dominique Crenn’s recipes, only to find out that 99.9% of her recipes called for things that an everyday home cook would not own, and for her most do-able recipe to be French macarons. This recipe, as I typed it out, gave me those same vibes of general unapproachability, and I get it, not everyone owns a siphon or silicone molds, not every is willing to ball out and buy black currant concentrate and powder, and ruby chocolate. For me personally, it just so happened that I actually owned all of these things because of previous recipes or just previous experimentations in general resulting in me having those items in my pantry. But hopefully even just one of the components or techniques could be used as inspiration for a dessert that you want to try making in your near future.

Makes 4 petit gateau:
For the black currant gelee:
1oz black currant concentrate
2 tsp agar
a pinch of salt

Bring everything to a simmer. Once the agar is fully dissolved into the concentrate, divide the concentrate into four 2-inch silicone cylinder molds. Freeze for at least 10 minutes.

For the Nutella ganache:
2oz Nutella
1/2 tsp gelatin powder + 1 tbsp cold water
2 tbsp heavy cream
1oz dark chocolate
a pinch of salt

In a pot, melt down the Nutella with gelatin, cream, chocolate, and salt. Once everything is dissolved, transfer the mixture into a bowl and allow it to cool down slightly before pouring over the gelee disks, all still in the silicon cylinder molds. Smooth off the tops using an offset spatula, and then freeze the two into solid pucks, for at least 2 hours.

For the dark chocolate cake:
1oz dark chocolate, melted
1 tbsp canola oil
1 tbsp Nutella
1 tbsp cocoa powder
2 eggs, separated
3 tbsp granulated sugar
1/4 cup all-purpose flour
1/4 tsp baking powder

Over a double boiler, melt together the chocolate, vanola oil, Nutella, and cocoa powder. Once everything is mixed together, whisk into that your egg yolks. In a separate bowl, whip the egg whites with sugar to stiff peaks. Sift into the chocolate mixture the flour and baking powder, then fold into that the egg whites. Pour and spread the batter on a lined quarter sheet tray into a thin and even layer. Bake at 350 degrees F for 12 minutes. Cool down before cutting out 2-inch disks.

For the cake soak:
2 tbsp milk
a pinch of salt

Mix to form your soak. Keep refrigerated until initial assembly.

For the black currant mousse:
3.5oz black currant concentrate
2 tsp gelatin powder + 1 tbsp cold water
2oz white chocolate chips
2oz ruby chocolate
a pinch of salt
1 tsp vanilla extract
6oz heavy cream, whipped to stiff peaks

In a pot, melt down the black currant concentrate, gelatin, chocolates, and salt. Once everything is fully dissolved together, pass through a sieve to remove any lumps. Allow the mixture to cool down to room temperature before adding in the heavy cream in two parts. Transfer the mixture to a piping bag to begin initial assembly.

Initial assembly:
Using silicone petit gateau molds, start by piping in generous amounts of the mousse into 4 of the molds. Press into those your Nutella ganache and black currant gelee inserts, pressing them in Nutella ganache side-down. Using an offset spatula, scrape off any excess, reserving all of your leftover mousse(you will be re-melting that down to make your glaze). Brush the cakes with the soak and press them against the openings of the petit gateau molds. Freeze these solid, at least 3 hours, before attempting to unmold and glaze.

For the Nutella micro-cake:
2 eggs
1.5oz Nutella
.75(3/4)oz sugar
A pinch of salt
.375(3/8)oz all-purpose flour
3 CO2 cartridges
black currant powder*

In a bowl, whisk together the eggs, Nutella, sugar, and salt first. Once everything is fully combined, fold in the flour. Transfer your batter to a foaming gun/siphon, and charge with 3 CO2 cartridges, shaking the siphon vigorously between each charge. Line 3 microwave-safe paper cups with a thin layer of cooking spray, and using a knife, poke holes into the bottom of the cups. Fill each cup about halfway with the batter, and then microwave for 1 minute. Cool the cakes, with the cup being placed upside down, for 1 minute before removing from the cup and tearing into smaller pieces. Dust the finished cakes with black currant powder if desired.

For the ruby chocolate glaze:
4oz leftover mousse
2oz white chocolate
2oz ruby chocolate
1oz water + 1 tbsp gelatin powder
1oz black currant concentrate

In a pot, melt down the mousse on low heat first, then add in the remaining ingredients. Stir occasionally for 2 minutes on low heat, allowing everything to melt together into one smooth, cohesive liquid. Pass through a sieve to remove any lumps. Keep the glaze around 90 degrees, and claze the petit gateau while they are still frozen for optimal results!

For the ruby chocolate garnish:
2oz ruby chocolate
a pinch of salt

Over a double boiler, melt 1.5oz of the ruby chocolate with salt completely. Once the chocolate registers 120 degrees F, take the bowl off heat and stiff in the rest of the ruby chocolate. Continue to stir until the mixture registers 90 degrees F. Transfer to a ziplock bag. Fill a bowl with ice and water. Cut a small bit off the end of one ziplock bag and begin piping circles of the ruby chocolate into the ice, allowing them to sink to the bottom of the ice water. Repeat until you have at least 8 good circles(this way you get to choose which ones you want to use!).

For final assembly:
Place the still-frozen petit gateau on an elevated surface – I used flat-ended piping tips, although tall and small cookie cutters work nicely here too! Pour the glaze over the petit gateau, allowing the excess to drip off the sides and for the glaze itself to firm up – roughly 2-3 minutes after pouring the glaze should suffice. Transfer the glazed petit gateau to your desired serving surface, and then garnish the tops with the micro-cake, then the ruby chocolate to finish.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s