For the genoise:

16 tablespoons unsalted butter, preferably uncultured
6 tablespoons chestnut flour
4 tablespoons cornstarch
6 tablespoons tapioca flour
2 teaspoons baking powder
3 teaspoons guar gum
8 eggs
1 cup and 2 tablespoons granulated sugar
2 ½ teaspoons vanilla extract

Preheat oven to 350°F and line a half-jellyroll sheet with parchment and liberally grease the parchment with unsalted butter. Set aside.
In a heavy bottomed saucepan, melt the butter over a low flame. Be sure to remove the butter from the heat the moment the last bit of butter has become liquid. Allow butter to cool while you prepare the eggs.
In a stand up mixer with the whisk attachment, whip the eggs until they begin to froth and then add the granulated sugar and the vanilla and whisk on the highest setting for five minutes. The eggs should be engorged with air at this point and at least double in size.
Sift together the dry ingredients. Fold in the dry ingredients and then fold in the cool, melted butter. Only mix the batter until all the ingredients are incorporated.
Pour the batter onto your prepared jellyroll sheet pan and bake at 350°F for 15-20 minutes. The cake should pull slightly away from the sides of the pan and should feel like a very delicate sponge when gently pressed with your finger. Allow to cool in the pan before cutting out your heart shaped little cakes. While cake is cooling, make the vanilla buttercream.

For the buttercream:

4 large egg yolks
¾ cup granulated sugar
6 tablespoons water
250 grams unsalted butter
1 ½ teaspoons quality vanilla

In a heavy bottomed saucepan, melt the sugar in the water and boil until it reaches 239ºF (soft-ball stage on candy thermometer).

While your simple syrup comes to temperature, whip egg yolks in standup mixer with the whisk attachment until combined. When the sugar reaches soft-ball stage, immediately pour all of the syrup into the egg yolks and whip on the highest setting until the yolks for uniform, thick mousse. Add the vanilla and whip just enough to combine.

In a separate bowl, whip the butter until light and smooth. Pour the cooled egg yolk mixture into the butter and whip until smooth.

Using a firm spatula, transfer the buttercream to a piping bag fitted with a #808 tip and set aside until you have cut out hearts.

Take a heart-shaped cookie cutter of your choosing, and cut out hearts from cooled genoise.

Carefully pipe the buttercream over the tops of the hearts, keeping in mind that the pattern you choose will be seen through the glacee.

For the glacee:

2 cups confectioner’s sugar
6 tablespoons water
1 ½ teaspoons chestnut extract

Sift all the confectioner’s sugar in a large bowl. Whisk in chestnut extract and water until smooth.

After you have piped the buttercream over the tops of hearts, flood the tops of each cake until the entire cake has a uniform coating of icing.

Refrigerate until ready to serve.
Makes 7-8 hearts.