Start with a pre-baked pie crust, allowing it to cool completely.

In a mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3-5 minutes.

Sift in the cocoa powder and mix until well combined.

Add the eggs, one at a time, mixing well after each addition.

Mix in the vanilla extract until fully incorporated.

Spoon the chocolate mixture into the cooled pie crust, smoothing the top with a spatula.

Cover the pie with plastic wrap and refrigerate for at least 4 hours or overnight.

Before serving, whip the heavy cream to soft peaks and spread it over the pie.