Cook the cherry jam according if using home made. See note 1 for the recipe I used.
Preheat the oven to 175 degrees Celsius.
Line or greaser a 18 cm spring form.
Combine oat flour, hazelnut flour, cacao powder, baking powder and baking soda in a bowl.
Separate the eggs. Add the egg yolks to a bowl, save the egg whites for later.
Whisk egg yolks and sugar together until fluffy using an electric whisk.
Add mashed banana, apple sauce, ricotta and hazelnut butter and whisk to combine. Do not whisk for too long.
Next add the dry ingredients and stir gently to incorporated.
Add egg whites in a clean bowl with a pinch of salt. Whisk using a clean whisk until stiff peaks start to form.
Gently fold in a little bit of the the egg whites to the batter, gently stir to combine. Add the rest of the egg whites and gently stir to incorporate them. Do not overman, just until incorporated and no white streams from the egg whites show.
Pour into the prepared spring form. Bake in the oven for 30-40 minutes, until a knife or toothpick comes out clean.
Take out and let the cake cool before removing it from the spring form and cutting it.
Add Creme fraiche and sugar (if using) in a bowl and whisk until the Creme fraiche is fluffy and light.
When ready to serve top the cake with about one tablespoon of whipped Creme fraiche on each slice and top with about one teaspoon of cherry jam.