Chop the chocolate and melt over a warm water bath. Cream 175 g butter, 175 g sugar and vanilla sugar with the whisk of the hand mixer. Stir in 3 eggs one after the other. Mix flour and baking powder and stir in alternately with 50 ml milk.
Stir in chocolate.
Cream the ricotta, 50 g sugar and starch with the whisk of the hand mixer. Stir in 1 egg. Fill approx. 2/3 of the chocolate dough into a greased, floured box form (approx. 12 x 22 cm).
Brush the dough up at the edges and pour the cheese mixture into the depression. Mix the remaining dough and 1 tbsp. milk and spread carefully on the cheese mixture. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see
manufacturer) bake for about 45 minutes.
Take the cake out of the oven and let it cool down on a cake rack. Turn out while still lukewarm and let it cool down. Caramelise 100 g sugar in a wide pot until golden brown. Add 50 g butter and 1 tbsp. milk and simmer until the mixture is smooth.
Add the popcorn and mix loosely. Spread the caramel popcorn on the cake, drizzle the remaining sauce over it and let it cool down for about 30 minutes. Sprinkle with sea salt. Cut the cake into pieces and serve.