For the vanilla ice cream base, place the milk, cream and approx. ⅘ of the sugar in a saucepan and heat. Slit the vanilla pods lengthwise and scrape out the pith. Add the pulpand pods to the pot. Bring to the boil briefly, remove from the heat and leave to cool for 1 hour.
Separate the eggs. Beat the egg yolks with the remaining sugar over a hot water bath until foamy. Remove the vanilla pods from the cooled milk-cream mixture. Reheat the milk-cream mixture and then fold into the egg yolk-sugar mixture in a thin stream, stirring constantly. Stir over a hot water bath for about 10 minutes until thick and creamy.
Then place the bowl on a pan of ice water or let it cool completely in the refrigerator. Stir occasionally. Then put the mixture in an ice cream maker and freeze for 40-60 minutes until creamy.
In the meantime, prepare the brownie base. Preheat oven to 170 °C top/bottom heat (convection oven 150 °C). Line the baking pan with baking paper. Coarsely chop the chocolate and melt it together with the butter over a hot water bath. Allow to cool slightly.
In the meantime, beat the eggs with the sugar and vanilla sugar with the help of a hand mixer until foamy. Combine the cinnamon, baking powder, cocoa and flour in a bowl. Stir the still-warm chocolate-butter mixture into the egg-sugar mixture, then stir in the flour mixture on low speed. Pour brownie batter into the baking pan and bake in the oven for 20-23 minutes on the middle rack. Cut two circlesof about 10 cm in diameter from the finished brownie batter.
Remove about ⅔ of the ice cream mixture from the ice cream maker and place in a precooled bowl, the diameter of which is slightly smaller than the brownie circles. Finely chop the frozen berries in a food processor and incorporate them into the ice cream mixture, finally smooth the surface and freeze in the freezer for 3-5 hours. Finely chop the nuts as well and mix them with maple syrup in a hotpan and immediately add them to the rest of the ice cream mixture in the ice cream maker. Freeze in the ice cream maker for another 10 minutes. Then pour into a round, shallow mold with a diameter of 10 cm, smooth and putin the freezer.
For the meringue, sift the granulated sugar. Separate the eggs and beat the egg whites with a pinch of salt in a metal bowl over a hot water bath until stiff. Meanwhile, slowly add the granulated sugar. Remove the beaten egg whites from the bain-marie and chill for another 5 minutes.
Layer the ice cream cake as follows: Brownie base, vanilla nut ice cream, and vanilla berry ice cream. Spread the meringue over the ice cream dome in waves with a pastry scraper and flambé briskly with a gas burner until light. Serve immediately.