Step 1

Heat chocolate in a microwave-safe bowl in 20-second intervals, stirring between, until completely melted. Set aside and let cool for about 10 minutes until it is room temperature.

Step 2

In the bowl of an electric stand mixer using the paddle attachment, cream together butter and sugar on medium-high speed until fluffy, about 1-2 minutes. When melted chocolate has cooled, gradually add it to the butter/sugar mixture. Add the espresso powder (if using). Beat the mixture on medium-low speed until thoroughly until combined. Add vanilla and beat until combined.

Step 3

Switch to the whisk attachment. Add one egg, and beat for 5 minutes on medium speed. Repeat with remaining three eggs, beating the mixture for an additional 5 minutes after each egg. (20 minutes total.) Pour the filling into a baked pie shell in a pie plate, and use a spatula to spread out the top evenly. Refrigerate for at least 2 hours or until chilled before serving.

Step 4

Top with desired amount of whipped cream, then garnish with chocolate shavings or curls.

Step 5

*This ingredient does use raw eggs.  Consume at your own risk.