Prepare 2 aluminium moulds or a 23 cm (9 inches) diameter cake tin: grease and sprinkle with flour. If you are baking in a cake tin, apply paper to the bottom of the tin by fastening the rim and letting the paper out.
Dissolve the butter with chocolate. In a separate bowl, mix the sugar (150 g) with the yolks using a whisk and add them to the mix of chocolate and butter. Stir the mixture with sifted wheat and potato flour. Separately whisk the whites while gradually adding sugar (20 g). Pour the whipped whites into the mixture. Split the whole into 2 parts. Bake in 160° C (320° F), up and down, for about 30-40 minutes until obtaining the so-called “dry skewer stick”. Extend the cooking time if necessary. Cool the baked layers of the cake on a cooling rack.
Pour the water into the gelatine and leave to swell. Pour milk into a saucepan with a thick bottom, add 1 tablespoon of sugar and heat it. In the meantime, mix the sugar with egg yolks in a separate bowl using a whisk. When the milk reaches about 80° C (180° F), pour 1/3 of the milk into the yolks, stirring constantly. When the temperature is even, pour the mixture of yolks into the saucepan with milk. Stir with a wooden spoon until the cream thickens slightly. Remove the cream on the yolks from the burner. Add chopped chocolate and swollen gelatin. Wait approx. 1 minute and mix well until the ingredients are completely mixed. Leave the cream to cool down completely.
Wash and them the strawberries and cut them into halves. Place the first layer of the cake in the rim of the cake tin. Soak with coffee. Place the strawberries with the inner sides pointing towards the edge.
Stir the cream briefly and spread the first part on the cake, to the level of strawberries. Apply another layer of the cake, soak it and apply the remaining cream to the top. Decorate with strawberries, mint leaves and meringues.