Separate eggs. Beat the egg whites and 3 tbsp. cold water until stiff, adding sugar. Stir in egg yolks briefly. Mix starch, flour and baking powder. Sift the flour-mix over the mixture and fold in. Spread the sponge mixture evenly on a baking tray (approx. 32 x 39 cm) lined with baking paper. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 8 minutes. Remove and turn out onto a tea towel sprinkled with sugar. Remove the baking paper. Let it cool down
Cut the sponge cake plate in three. Stir the jam until smooth. Knead marzipan with 2 tbsp. liqueur. Roll out rectangularly (approx. 32 x 13 cm) on a work surface dusted with icing sugar. Spread 1 tbsp. liqueur on each side of the marzipan plate and place on a sponge cake plate. Place the second plate on top and spread with jam. Place the third plate on top. Weigh down with a board and chill for about 1 hour
Chop the two types of envelope door separately. Add about 20 g coconut oil to the dark chocolate coating and melt over a warm water bath. Add 5 g of coconut oil to the white couverture and melt carefully
Cut the edges of the cake plate straight. Cut into approx. 21 squares (approx. 4 x 4 cm). Cover the petit fours with the dark chocolate coating. Let dry on a cake rack. Pour the white couverture into a piping bag. Decorate the petit fours with it and leave to dry. Decorate with letter plugs
waiting time approx. 2 1/2 hours