**Preheat and Prepare:** Preheat your oven to 350°F (175°C). Grease a 9-inch pie pan or line it with parchment paper for easy removal.
**Make the Brownie Layer:** In a mixing bowl, combine melted butter and sugar. Whisk in the eggs until smooth. Add cocoa powder, flour, salt, and baking powder. Stir until just combined. Spread the brownie batter evenly into the prepared pie pan.
**Make the Pumpkin Cheesecake Layer:** In another bowl, beat the cream cheese and sugar until smooth. Add the egg, pumpkin puree, vanilla extract, and pumpkin pie spice. Mix until fully incorporated.
**Layer the Pie:** Gently pour the pumpkin cheesecake mixture over the brownie layer, spreading it evenly with a spatula.
**Bake:** Bake the pie for 40–45 minutes, or until the cheesecake layer is set and a toothpick inserted into the brownie layer comes out with a few moist crumbs.
**Cool and Chill:** Allow the pie to cool completely at room temperature, then refrigerate for at least 3 hours before serving.
**Add Toppings:** Top with whipped cream, chocolate shavings, or a sprinkle of cinnamon, if desired.