Melt & Mix: In a medium saucepan over medium heat, melt the butter.
Combine Dry Ingredients: In a bowl, whisk sugar, flour, and cocoa until uniform.
Build the Base: Gradually whisk the dry mix into melted butter until smooth.
Add Milk: Slowly whisk in the milk, breaking up any lumps.
Thicken: Cook, stirring constantly, until the mixture comes to a gentle boil and thickens—about 1 minute.
Temper the Yolks: In a small bowl, whisk egg yolks. Slowly drip in ≈½ cup hot chocolate mixture, whisking constantly.
Finish the Filling: Stir the tempered yolks back into the saucepan. Cook 1–2 more minutes over medium-low, stirring, until very thick. Remove from heat and stir in vanilla.
Fill the Crust: Pour hot filling into the baked crust; spread evenly.
Whip the Meringue: In a clean bowl, beat egg whites and cream of tartar on medium until foamy. Gradually add sugar, beating on high until stiff, glossy peaks form.
Top & Bake: Mound or pipe meringue over the filling, sealing to the crust edge. Bake at 350°F (175°C) for 12–15 minutes, until golden.
Cool & Serve: Let the pie cool completely on a wire rack to set before slicing.
Extra Tips & Variations:
Prevent Weeping: Seal meringue fully to crust edges to lock in moisture.
Flavor Twist: Stir a tablespoon of strong coffee into the filling for a mocha note.
Mini Versions: Bake in 4-inch tart pans for individual desserts.
Dairy-Free Option: Use almond-milk and dairy-free margarine for a vegan-friendly pie.
