Mix the flour with the baking powder, sugar, and salt. Add the rest of the ingredients one-by-one, excluding the chocolate, and knead everything into a smooth dough. Carefully fold the chocolate into the dough and refrigerate. Line the baking tin with food wrap, press the dough cookie into the base, fold the remaining wrap on top of it, and remove it from the pan. Place the disc of cookie dough back in the refrigerator.
Melt the chocolate, butter, and sugar in a water bath. Carefully stir the mixture and leave it to cool. Whip up the eggs and stir them into the chocolate mixture. Carefully mix all the dry ingredients together and stir it into the chocolate mixture.
Grease the springform pan with some oil. Fill the pan with the brownie batter, grease the bottom of a large pot on the outside, and place it in the dough. Bake everything at 325°F for 25 minutes in a convection oven.
Carefully remove the pot from the dark batter and place chocolate cookies in the space that has been created.
Whisk the cream cheese with the sugar, vanilla extract, and egg until a smooth creamy mixture forms. Pour this onto the cookies and smooth everything flat. Bake the cake at 325°F for 25 minutes. Leave the cake to cool before refrigerating it again.
Add another layer of cookies onto the cheesecake filling and place the cookie dough disc on top. Remove the food wrap and press the cookie dough into the cake using your fingers. Bake everything at 325°F for another 25 minutes.
Leave the cake to cool again before removing it from the pan and decorating it. Pipe some whipped cream onto each portion and place another chocolate cookie on top.