I love langue de chat. They’re probably better known as the shiroi koibito cookies(think like a square shaped Milano with a large chunk of white chocolate filling in them), since those are probably the most popularly served iteration of them. Think thin, buttery cookies with a melt in the mouth texture. They are surprisingly easy to make, with the only difficulty being the equipment – the batter itself is mostly sugar, butter, an egg white, and flour, but if you want super consistent and neat cookies, you will need a square-shaped stencil and either an offset spatula, or preferably a bench scraper. The batter used for these cookies is basically a tuile batter, but by pressing it through a square stencil, they are slightly thicker than your standard tuile. The filling, depending on which route you go, requires a lot of patience, since you need to freeze it solid in the same stencils you used to shape the cookies so that they are easier to sandwich between the cookies themselves. I still remember back in early 2020, when my mom brought some back from her visit to Japan for me, and I was so entranced by them that I attempted to make them, without having a clue on how to do that. My interpretation was completely off, being a shortbread sandwich cookie instead. But with more baking practice and knowledge, I was able to get there. And trust me, these cookies are by no means difficult to make! If you have the right equipment, and a little bit of patience, you can make those delicious shiroi koibito cookies from the comfort of your own home too!

For this flavor, I wanted to be extra, and make the cookies with yujacha, or yuzu marmalade. I subbed out the sugar with the yujacha, and it actually flavored the cookies quite nicely. The one thing I will warn about is that yujacha usually comes with large chunks of peel in it. So I recommend chopping the yujacha very finely before adding it into the batter. This is because when you go to spread the batter in the stencil, if there are large chunks of peel in there, that will get caught, and you will end up with a giant mess. The same goes with the buttercream. I went with a yuzu French buttercream, using yujacha, yuzu juice, and Valrhona yuzu inspiration(essentially yuzu-flavored white chocolate), to flavor it. I also folded in some blueberry jam into my buttercream, just to give it a pleasant pink hue, and since I love the combination of blueberry and citrus. Again, the same warning applies here with the consistency. Make sure you finely chop up the marmalade and the blueberry jam, otherwise when you try spreading the buttercream with those things folded through it, it will just pull and smear weirdly, and won’t really even go into the molds. Traditional shiroi koibito langue de chat feature a white chocolate-butter filling, but in this case, I went with a French buttercream, since a. I had an egg yolk leftover from making the batter I wanted to use up, and b. it is a lot easier to flavor a French buttercream than try introducing more ingredients to white chocolate that would potentially mess up the chemical makeup of it. I will suggest using lightly oiled parchment as the surface you spread the buttercream on, which will make for faster assembly.

Makes 22 to 24 cookie sandwiches
For the cookies:
3 tablespoons butter, room temperature
1.5oz yujacha(yuzu marmalade), chopped finely
1 egg white
1/2 teaspoon vanilla extract
a pinch of salt
2/3 cups all-purpose flour

In a bowl, whip the butter, yujacha, egg white, vanilla, and salt together until combined. Fold into that the all-purpose flour to form your batter. Allow your batter to rest for at least 1 hour – this will help the batter from contracting when you are spreading it. Spread the batter onto a parchment or silicone-lined sheet tray using a square cookie stencil. Repeat this process until you have used up all your batter. Bake the cookies, one sheet tray at a time, at 375 degrees F for 7 minutes. Allow the cookies to fully cool before attempting to use.

For the yuzu-blueberry French buttercream:
1 1/4oz yujacha, chopped finely
A pinch of salt
1 tbsp yuzu juice
1oz Yuzu Inspiration
1 egg yolk
5 tbsp unsalted butter, room temperature
1/4 tsp vanilla
1 tbsp blueberry jam, chopped finely

In a pot, bring the yujcaha, salt, and yuzu juice to a simmer. Add to that the Yuzu Inspiration, stirring until melted together. Pour that liquid over the egg yolk and being whisking until combined. Whisk into that the butter and vanilla, whipping until everything has been mixed together into a homogenous, creamy, smooth mixture. Swirl the blueberry jam into the buttercream as well. Using the same square stencils as with the cookies, spread the buttercream into the stencils onto a nonstick surface(preferably parchment, but silpat works too), repeating until you have used up all of the buttercream. Freeze the buttercream for at least 30 minutes, if not longer, before attempting to press between two cookies.