Annie Lou’s Chocolate Meringue Tarts look fancy but don't take forever

This is part of Southern Kitchen's 12 Days of Cookies and Cocktails series, which runs daily through Christmas Eve. Each day, we'll pair fun and festive cocktails with classic cookie recipes.
We've paired these gorgeous tarts with this elegant run and espresso drink.
About the recipe
This is a sophisticated dessert that would be marvelous if served after a lavish holiday meal.
A word on meringue: Older egg whites are unlikely to hold air bubbles as well as fresher whites will. To avoid collapse, use fresh, just-cracked eggs, but get your eggs to room temperature before you crack them.
Also, make sure your bowl is spotlessly clean, as a dirty bowl can keep your meringue from coming together.
You can use pre-made pastry shells in this recipe or make them yourself.
This recipe originally appeared in Anne Byrn’s Taste of a Place column.
Serves: 10 to 12
Hands On Time: 30 minutes
Total Time: 1 hour and 30 minutes
Ingredients
10 to 12 (3-inch) frozen unbaked pastry tart shells or 1 (9-inch) frozen unbaked pie shell
1 cup plus 6 tablespoons granulated sugar
1/3 cup all-purpose flour
1/4 teaspoon salt
2 cups whole milk
2 ounces unsweetened chocolate, chopped
3 large eggs, separated
1 to 2 tablespoons unsalted butter
1/2 teaspoon vanilla extract
1/4 teaspoon cream of tartar
Instructions
Place a rack in the center of the oven and heat to 425 degrees.
Place the frozen tart shells in their aluminum pans on a baking pan. Prick the shells with a fork a few times on the bottom and sides. Bake until the shells are golden brown, 8 to 10 minutes. Let cool completely before removing the shells from their pans. (If using a 9-inch pie shell, follow package directions for baking.) Reduce the oven temperature to 350 degrees.
For the filling, whisk together 1 cup of the sugar with the flour and salt in a small bowl.
In a medium saucepan, heat the milk over medium heat until it just begins to steam, about 2 minutes. Remove from the heat and stir in the chocolate until it melts. While whisking constantly, gradually pour the sugar mixture into the chocolate mixture until smooth. Place the pan back over medium heat and cook, whisking constantly, until the mixture has thickened, about 2 minutes. Remove from the heat.
In a medium bowl, whisk together the egg yolks. While whisking constantly, pour a generous tablespoon of the hot chocolate mixture into the yolks. Whisk the egg yolk mixture into the remaining hot chocolate mixture until smooth. Place the pan over low heat and cook, whisking constantly, until thick and smooth, about 2 minutes. Remove from the heat and stir in the butter and vanilla.
Meanwhile, prepare the meringue: In a large bowl, beat the egg whites and cream of tartar with an electric mixer on high speed until soft peaks form, about 2 minutes. While the mixer is running, pour in the remaining 6 tablespoons sugar, and continue beating on high until stiff peaks form, 1 to 2 minutes.
Ladle the chocolate filling into the cooled tart shells and cover with meringue. Make sure the meringue meets the pie crust to completely cover the filling. Bake until the meringue is golden brown, 10 to 12 minutes.
Let the tarts cool for at least 15 minutes. When cool enough to handle, lift the tarts out of their aluminum pans, and place on a rack to cool completely. Serve.