Process:

1. Preheat oven to 350 F.
2. To start, make the pie crust by adding flour, cocoa powder, sugar and salt in a bowl and mix to combine.
3. Transfer to a food processor and add the cold butter. Pulse until butter mixture has a crumbly consistency.
4. Pour the cold water one tablespoon at a time into the dough until the dough comes together (you may not use all the  water). 
5. Turn the dough out on a flat, lightly floured surface and roll out into a disc that will fit into a 9 inch pie dish. 
6. Press the dough sheet into a lightly greased pie dish using your fingers and refrigerate until your cheesecake filling is ready. 
7. Next, make your filling by beating the mascarpone on medium-low speed using a hand or stand mixer until smooth (1-2 minutes).
8. Add ricotta and sugar and beat until combined and smooth.
9. Beat in eggs, one at a time, until fully combined. Add cornstarch, cream, vanilla extract, and zest, and beat just until blended. 
10. Pour filling into the crust and spread evenly. 
11. Next make your crumb topping by mixing brown sugar, flour, cocoa and butter in a small bowl until crumbly. Stir in chocolate chips. Sprinkle over cheesecake.
12. Place cheesecake carefully in the oven on the middle rack and bake for 50-60 minutes or until sides of the cheesecake are set but the center is still slightly jiggly. 
13. Transfer pan to a wire rack and allow to cool completely.
14. Cover cheesecake with plastic wrap and refrigerate for 8 hours to set. Note: This cake will taste best the next day after setting!
15. Store in the fridge up to 5 days.