Microwave Chocolate Pie

Preheat the oven to 375 degrees F (190 degrees C).

Mix 3/4 cup sugar, 1/2 cup milk, cocoa, cornstarch, and salt together in a 1 1/2-quart microwave-safe dish until smooth. Stir in remaining milk. Microwave on high until thick, 5 to 8 minutes, stirring halfway through.

Beat egg yolks in a small bowl. Pour a small amount hot chocolate mixture into the bowl, whisking quickly to avoid scrambling the eggs. Pour mixture back into the microwave-safe dish and whisk until incorporated. Microwave on high until thickened, 1 1/2 to 2 minutes, stirring freqeuntly.

Remove from the microwave; stir in butter and 1 teaspoon vanilla. Pour mixture into pie crust.

Beat egg whites and cream of tartar in a glass, metal, or ceramic bowl until foamy. Gradually mix in remaining 6 tablespoons sugar, 2 tablespoons at a time, until stiff peaks form. Stir in remaining 1/2 teaspoon vanilla. Spread meringue over pie filling; cover the edges of the pie with aluminum foil.

Bake in the preheated oven until meringue is lightly browned, about 8 minutes.