Place the pie crust in a 9-inch pie dish, crimping the edges as desired. Prick the bottom with a fork to prevent bubbling. Set aside.
Make the Brownie Filling:
In a medium saucepan, melt the butter over low heat. Remove from heat and stir in sugar, eggs, and vanilla.
Beat in cocoa, flour, salt, and baking powder. Spread the brownie batter evenly into the pie crust.
Bake:
Bake in the preheated oven for 25-30 minutes, or until the center is set but still slightly gooey. Be careful not to overbake, as the filling should be soft and fudgy.
Cool and Serve:
Allow the pie to cool slightly before serving. The pie can be served warm or at room temperature.
For an extra indulgent treat, serve with vanilla ice cream, whipped cream, and a drizzle of chocolate syrup.