Place the condensed milk jar in a pot with plenty of water, bring to the boil, cover and simmer for about 1 1/2 hours. Remove from the pot and let it cool down
Mix flour, baking powder, cocoa, sugar, vanilla flavouring and salt. Add 1 egg, butter in small pieces and about 1 tablespoon of cold water. Knead with your hands to a smooth shortcrust pastry. Wrap the dough in foil and chill for about 20 minutes
Grease a flat rectangular casserole dish (approx. 15 x 28 cm, rim approx. 4 cm high). Cut a strip of baking paper to the length of the dish and place it in the dish so that the paper protrudes 3-4 cm over the edge on the long sides. Roll out the dough on a lightly floured work surface to a rectangular plate (approx. 22 x 34 cm) and place in the form. Cut off any excess dough all around. Prick the dough base several times with a fork, line with baking paper and fill in peas. Bake in the preheated oven, lower shelf (electric oven: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 25 minutes. After about 10 minutes, lift the peas out of the tin with the baking paper. Finish baking the dough
In the meantime, heat the double cream and milk in a saucepan and remove from the heat. Roughly chop the chocolate and melt in it while stirring. Whisk 2 eggs in a bowl. Stir the chocolate mixture into the eggs
Remove the mould from the oven and reduce the temperature (electric cooker: 150 °C/ circulating air: 125 °C/ gas: see manufacturer). Open the condensed milk jar and spread the thickly boiled mixture on the shortcrust pastry base. Spread the chocolate mixture on top. Place the tart on the middle shelf in the hot oven and bake for approx. 10 minutes. Switch off the oven (do not open), leave the tart to stand for about 1 hour. Remove the tart, let it cool down for about 4 hours (if necessary, put it in a cool place for a short time). Lift the tart out of the tin and dust with cocoa as desired. To serve, cut into 2-3 cm wide strips and then halve them.
waiting time approx. 4 1/4 hours