Heat 200 g cream. Caramelise 150 g sugar. Carefully stir in hot cream and 2 tablespoons of butter, bring to the boil and simmer for about 5 minutes until the caramel is creamy. Remove from the heat and let it cool down.
Grease a springform pan (26 cm Ø) and dust with flour. Roughly chop the chocolate and put 50 g aside. Melt the rest of the chocolate and 250 g butter in a saucepan over low heat.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Mix cocoa, 65 g flour, baking powder and 350 g sugar in a bowl. Fold into the chocolate mixture. Beat the eggs and 1 pinch of salt with the whisk of the mixer for approx. 5 minutes until thick and creamy, stir into the chocolate dough.
Fill half of the dough into the mould. Pre-bake in the oven for about 15 minutes. Take out and let it cool down a little. Coarsely chop the nuts and spread them on the dough. Put 2-3 tbsp. caramel aside, spread the rest on the dough, leaving about 1 cm of edge free.
Sprinkle with the rest of the chopped chocolate. Spread the rest of the dough on top. Continue baking at the same temperature for about 20 minutes.
Let the brownie cool down. Cut into pieces and sprinkle with remaining caramel. Serve with a fruit salad of oranges and physalis.