Prepare the oven and pan
Preheat the oven to 375°F (190°C). Lightly grease a 9-inch pie dish (glass or metal) with butter or nonstick spray.

Make the crust dough
In a bowl combine the almond flour, cocoa powder, baking powder, salt and sweetener. Cut in the cold butter with a pastry cutter, fork, or pulse in a food processor until the mixture resembles coarse crumbs. Add the egg and vanilla, then mix until the pieces hold together when pressed. If using a processor, pulse a few times until it forms a cohesive dough.

Press and bake the base
Press the dough evenly across the bottom and up the sides of the prepared pie dish, packing it firmly so the crust will hold its shape. Bake for 10–15 minutes, until the crust is set and slightly fragrant. Remove from the oven and allow the crust to cool completely on a rack.

Make the chocolate filling
In a large bowl beat the softened cream cheese until smooth. Add the sour cream, cocoa powder, sweetener and vanilla and continue beating until blended. Slowly mix in the melted dark chocolate, then fold in the heavy whipping cream and whip briefly until the filling becomes light and fluffy (about 3–4 minutes with an electric mixer). Taste and add a little more sweetener if you prefer it sweeter.

Fill the crust and chill
Spoon the chocolate mixture into the cooled crust and smooth the top. Cover and refrigerate for at least 6 hours (overnight yields the best texture) so the filling firms up.

Whip the topping
Shortly before serving, whip the 3/4 cup heavy cream with the powdered sweetener and vanilla until soft peaks form. Spoon or pipe the whipped cream over pie slices, then finish with chocolate shavings or a dusting of cocoa.