Aurora: a “glow-in-the-dark” entremet

So before I get into the rest of this post, I want to clarify the technical misnomer of this cake. I used tonic water, which allows the cake to glow under black light. Different than actually glowing in the dark, but still really cool. That being said, this is actually the second time I have done a cake like this(though the first time, I had no black light so I didn’t even get to show off the coolest part of said cake). So with this particular cake, I was inspired by aurora borealis, hence the name of the cake reflecting that. I wanted to use flavors from regions of the world where aurora is normally seen, hence why I went with the Nordic fruit sea buckthorn, as well as skyr, which is Icelandic yogurt. I prefer skyr to a Greek yogurt just because it has a rich, mousse-like texture. That and the last time I tried to make a mousse with normal yogurt, which has a higher water content, all of that excess water leeched out of the mousse and because a puddle under the cake. But since skyr is already strained, it has a denser texture and lower water content, so no leeching of water from the mousse.

With the decoration and appearance, I wanted the exterior of the cake to reflect the colors of the night’s sky when there is aurora present, but the interior to have a bright and sunny aesthetic, to reflect the night ending and the day beginning. For the bubble sugar itself, I made that and the mirror glaze with tonic water. Tonic water, while it tastes honestly horrendous, has a unique quality in that it can glow under black light. This is because it contains quinine, which allows the water to do that. I only included the water in the glaze, which will already have next to no flavor anyways, and the isomalt bubble sugar, which is basically just pure decoration as well. I don’t recommend actually eating the bubble sugar, because while it is technically edible, the tonic water doesn’t taste that good(but is still glows in black light, which is super cool!).

For the sea buckthorn gelee:
1/3 cup sea buckthorn puree
2 tablespoons agar agar
a pinch of salt

Bring ingredients to a simmer. Place a 5-inch and 3-inch ring mold onto a cling wrap-lined surface to form a ring-shaped mold. Pour the puree between the two molds. Freeze the puree for at least 20 minutes so that it is fully set.

For the skyr cake:
1/3 cup semolina flour
1/3 cup all-purpose flour
3 1/2 oz skyr yogurt
1/4 cup granulated sugar
1/4 cup olive oil
1 egg
1/2 teaspoon baking powder
a pinch of salt
1 teaspoon vanilla extract

Mix ingredients to form a batter. Pour the batter onto a parchment-lined quarter sheet tray and spread into a thin and even layer. Bake at 350 degrees F for 15 minutes. Allow the cake to fully cool before cutting out a 5-inch round of the cake.

For the skyr mousse:
1 1/2 teaspoons gelatin powder
1 tablespoon cold water
3 tablespoons milk
3 tablespoons granulated sugar
a pinch of salt
7 oz skyr yogurt
1 teaspoon vanilla extract
1/3 cup heavy cream, whipped to stiff peaks

Mix the gelatin with water. Place the gelatin, milk, sugar, and salt into a pot and bring to a simmer. Once the gelatin is fully dissolved into the milk, pour the liquid into the skyr and whisk it with the vanilla as well. Fold into that the cream. Line a 6-inch ring mold with oil and place onto a cling wrap-lined surface. Pour in about half of your mousse first. Press into that the ring of sea buckthorn gelee. Then pour in the rest of the mousse. Press into that the round of cake. Then freeze the cake for at least 4 hours before attempting to unmold.

For the tonic water glaze:
2 packets gelatin powder
1/2 cup cold tonic water, in two parts
3 tablespoons milk powder
1 cup white chocolate chips
purple food coloring
blue food coloring

Mix the gelatin with one part of the tonic water. Mix the rest in a pot with the milk powder. Place the gelatin into the tonic water-milk mixture and bring to a simmer. Once the gelatin is fully dissolved, take the pot off heat and stir in the white chocolate until it is fully dissolved. Dye half of the glaze purple, one fourth blue, and the rest, leave undyed. Keep the glazes at 90 degrees F, or reheat as necessary, when it is time to glaze. To glaze, place the still-frozen mousse cake, now unmolded, onto an elevated surface(I like to use a large, shallow bowl and a ring mold), and then pour the glazes over the cake. Allow the glazes to set, about 2 to 3 minutes at room temperature, before moving the cake to a serving surface.

For the tonic water bubble sugar:
1/2 cup tonic water
1/4 cup isomalt
gel food coloring

Reduce the tonic water with isomalt in a pot. Bring the two to a boil. Brush parchment with different gel food colors(I did green, blue, purple, and a small amount of red). Once the isomalt reaches 300 degrees F, pour onto the parchment and tilt the parchment so that the isomalt will spread out as a thin layer. Allow the isomalt to set, about 10 minutes at room temperature, before peeling away from the parchment, breaking into smaller pieces, and using to decorate.

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