Buckwheat and Blueberry Jam Cake

Method

1. Separate the egg whites from the yolks.
2. Add a portion of the sugar to the egg whites and the remaining sugar to the softened butter.
3. Whip the egg whites to stiff peaks.
4. Meanwhile, cream the butter with the sugar until well combined.
5. When the butter has absorbed the sugar, add the yolks and mix until creamy.
6. Stop using the whisk. Add the dry ingredients: buckwheat flour, almond flour, and hazelnut flour. Mix. (The mixture will be dry.)
7. Grate the apple and add it to the mixture.
8. Add lemon zest and instant yeast. Mix.
9. Fold in the whipped egg whites gently.
10. Prepare a 24 cm cake pan by lining the base with parchment paper and greasing the sides.
11. Pour the batter into the pan and level with a spatula.
12. Bake in a static oven preheated to 170°C for 40-45 minutes. Check doneness with a toothpick.
13. Once baked, remove from the pan and let cool on a wire rack.
14. Slice the cake horizontally into two layers.
15. Spread the black blueberry jam generously on the bottom layer, then cover with the top layer and press gently to adhere.
16. Dust with powdered sugar.