Preheat the oven to 180 degrees top / bottom heat and grease a baking sheet with butter.
Mix all ingredients for the dough with the hand mixer until creamy and spread on the baking sheet. Bake the cake for about 25 minutes on the middle rack in the 180 ° C oven.
Let 1/2 glass of apricot jam become a little liquid in the microwave for 30 seconds and spread thinly on the cooled cake base. Peel the bananas, cut in half and cut lengthways. Distribute them on the floor in a row.
Beat the cream with the cream stabilizer as usual. Mix the mascarpone with the powdered sugar and egg yolk until creamy and fold in the cream. Spread generously on the bananas and place covered in the fridge.
Cut the block chocolate into pieces with a large knife and melt slowly and not too hot in a water bath. Add the coconut oil or butter and stir well. Drizzle over the cake with a tablespoon until the chocolate is completely consumed.