Mix the Breton pancakes (or small butters) quite finely. Add the melted sweet butter and bitter cocoa to the biscuits and mix well.
Using a glass, pack this mixture onto the bottom and side of a round springform mold measuring 22 cm in diameter. Place in the refrigerator while you prepare the rest.
In a bowl, beat the Philadelphia cream cheese and ricotta to soften them. Then add the powdered sugar.
Separately, beat the whole eggs briefly with a fork then add to the previous mixture.
With a peeler, make shavings with the dark chocolate and the white chocolate. Add them to the preparation. Mix one last time to homogenize everything.
Pour the filling into the mold, on the biscuit base and bake for 1 hour 10 minutes. Leave the cheesecake to cool in the half-open oven, then refrigerate for at least 3 hours (all night is better).
Decoration
In a first saucepan, heat 100g of full-fat liquid cream and melt the white baking chocolate into small pieces. Smooth the resulting ganache well.
In a second saucepan, heat 100g of liquid cream and melt the dark baking chocolate into small pieces. Smooth the resulting ganache well.
To decorate the cheesecake, first pour the dark chocolate ganache, then the white chocolate ganache, then finish with a small circle of dark chocolate. To create a marbled effect, use a wooden pick or the tip of a knife to lightly mix the two colors of chocolate.
NB: like all cheesecakes, it will be even better if made 1 or 2 days in advance.