In a medium saucepan, combine granulated sugar, cocoa powder, all-purpose flour, and a pinch of salt. Gradually stir in 2⅔ cups of half and half over medium heat, cooking until the mixture thickens and begins to boil, about 5-7 minutes. Remove from heat. Temper the egg yolks by slowly mixing in a few spoonfuls of the hot mixture, then whisk back into the saucepan. Cook for 1 more minute until thick, then stir in chocolate chips and vanilla.

Preheat your oven to 375°F (190°C). In a clean mixing bowl, add 4 large egg whites and ¼ teaspoon of cream of tartar. Using an electric mixer, beat the egg whites on medium speed until soft peaks form, about 2-3 minutes. Gradually sprinkle in ⅓ cup of sugar, continuing to whip until you achieve stiff, glossy peaks, roughly another 2-3 minutes.

Once your chocolate filling has cooled slightly, carefully pour it into the baked 9-inch pie shell. Spread the whipped meringue over the filling, ensuring it touches the crust all around to prevent shrinking. Create swirls and peaks on top.

Place the assembled Chocolate Meringue Pie in the preheated oven. Bake for about 10 minutes or until the meringue is lightly golden on top. Let it cool on a wire rack for at least 1 hour. Refrigerate for a minimum of 4 hours before serving.