To prepare the pie:

1. Preheat the oven to 350 degrees.
2. Using a rolling pin, roll out the pie dough and transfer it into a 9” pie plate. Gently press the dough into the edges of the pan and trim off any excess. Crimp the edges as desired.
3. In a large bowl, whisk together the cocoa powder, flour, sugar, and salt until combined. Add the melted butter and sitr just to combine. Add the eggs, evaporated milk, vanilla extract, and vinegar and mix to combine. Pour the filling into the prepared pie crust and brush the crust with a bit of milk, beaten egg, or cream if desired. Bake the pie in the preheated oven for about 35 minutes or until the edges are well set and the innermost circle of pie is still just a bit jiggly. Remove and cool to room temperature.
4. Once cooled, prepare the whipped topping. Beat the heavy cream on medium speed in the bowl of a stand mixer fitted with a whisk attachment. Whip until frothy and slightly thickened and add the sugar and cocoa powder. Increase to high speed and beat until stiff peaks form. Spread dollops of the whipped cream on top of the pie and serve immediately.