Prepare the ingredients for the cake and the flan. Preheat the oven to 350°F (180°C).

Pour 1 cup sugar (about 200 grams) into the cake pan. Heat over medium heat until the sugar melts completely and turns into a golden caramel. Let cool and set aside.

For the flan mixture, place all the flan ingredients in a blender and blend for 5 minutes.

In a saucepan, combine the butter and chocolate. Melt together using a double boiler.

For the cake, beat the eggs in a bowl. When the eggs have doubled in volume, add the sugar and continue beating until stiff peaks form.

Next, add the remaining dry ingredients. Sift the powders well before adding. Gently fold everything together, then pour the cake batter into the pan with the reserved caramel.

Carefully pour the flan mixture over the cake batter. Do this slowly and gently so the layers don't mix. Cover with aluminum foil and bake at 350°F (180°C) for 1 hour and 20 minutes. (Baking time may vary depending on your oven. Check after 1 hour by inserting a wooden skewer; if it comes out clean, the cake is done.)