Instructions

Step 1: Combine Dry Ingredients and Yolks
In a heavy-bottomed saucepan, whisk together cocoa, flour (or cornstarch), beaten egg yolks, sugar, and salt until smooth.

Step 2: Cook the Custard
Gradually add the milk over medium-high heat, whisking constantly. Continue stirring for about 10 minutes, until the mixture thickens to a smooth, pudding-like consistency.

Step 3: Add Flavor and Butter
Remove from heat, then stir in vanilla extract and butter until fully incorporated.

Step 4: Fill the Crust and Chill
Pour the hot custard into the pre-baked pie shell. Refrigerate for several hours until the filling is completely set.

Step 5: Serve
Top with whipped cream if desired, or use leftover egg whites to make a light meringue topping before serving.