Preheat the oven at 175 degrees Celsius.
Butter the baking form with removable edges.
Spread evenly the bread crumbles in the form.
Mix the sugar and the eggs for 3 minutes in a bowl, use the highest speed on the electrical mixer for this.
In another bowl mix the flour, baking powder and potato flour.
Pour it slowly in the bowl with the egg mixture, while stirring with a wooden spoon.
Pour it in the baking form, and place in the lower part of the oven for 40 minutes.
Take out the bottom and let it cool down.
Cut the cake so you get 3 layers.
Place the bottom layer on the plate you're going to serve the cake on.
Time to make the filling. Start by spreading evenly the vanilla sauce on the bottom layer.
Place the middle layer on top.
With the electrical mixer mix the whip cream and vanilla sugar together.
Add the blueberries jam and mix together.
Spread it evenly on the middle layer. Put the top layer on top.
Time to make the topping. Start by mixing the whip cream and vanilla sugar to a foam with the electrical mixer.
Cover the top and sides of the cake with the whip cream.
Pour the rest of the whip cream in a piping bag and decorate the cake as you like.
Spread evenly the fresh blueberries on top of the cake.