Preheat the oven (electric cooker) to 175 °C. For the base, crumble the butter biscuits and cookies finely in a mixer and mix with the cocoa. Melt the butter and mix with the cookie crumbs.
Spread the biscuit mixture on the bottom of a coated springform pan 24 cm in diameter and press down well. Pre-bake the pastry base for about 7 minutes in the middle of the preheated oven and let it cool down.
Reduce the oven temperature to 130 °C.
For the filling, mix the cream cheese with the sugar and the scraped-out vanilla pulp until smooth. Gradually stir in the eggs.
Break the chocolate into pieces and melt over a hot water bath. Stir the melted chocolate, cream and rum into the cream cheese mixture. Pour the mixture onto the biscuit base and smooth it down.
Garnish with walnut halves.
Bake in the middle of the 130 °C hot oven for about 40 minutes. Let cool and serve lukewarm or cold.