Make the Pastry Cream

1. Heat the whole milk in a small saucepan over medium-low heat. Once the milk begins to steam and bubble around the edges, remove the pan from heat. We don’t want the milk to boil.
2. In a large bowl, whisk together the sugar, cornstarch, and egg yolks until the mixture turns a pale yellow (about 1 minute). Slowly pour the hot milk into the bowl of egg mixture, whisking constantly. If there are any large lumps in the mixture, pour it through a fine-mesh sieve before returning it to the saucepan.
3. Place the saucepan over medium-low heat. Cook the egg/milk mixture for 4 to 5 minutes, or just until it begins to boil and thicken. Whisk often so the mixture doesn’t scorch. When the pastry cream is thick enough to coat the back of a spoon, remove the pan from heat. Whisk in the vanilla extract. 
4. Transfer the pastry cream to a clean bowl. Cover the surface with plastic wrap. Make sure the plastic is touching the surface of the pastry cream to prevent a skin from forming on top. Put the bowl in the fridge and chill completely (about 2 hours).

Make Chocolate Ganache

1. Add the chopped chocolate to a medium bowl. Heat the heavy cream in a small saucepan over medium-low heat, just until it begins to steam. Pour the heavy cream over the chocolate. Let it sit for 1 minute. 
2. Whisk the chocolate and cream together until the ganache is thick and smooth. Set it aside to cool for 2 hours. In the meantime, make the crusts.

Prepare the Crusts

RECIPE PREP: Preheat oven to 400ºF. Grease 4 small (4″- 5″) tart pans with nonstick baking spray.

1. On your work surface, unroll the refrigerated pie crusts. Cut out 2 circles (about 6-inches in diameter) from each pie crust. 
2. Press one circle of dough into each prepared tart pan. Make sure not to stretch the pie crust or it will shrink when baked. Poke the bottom of each tart shell with a fork. You can fill the tart shells with pie weights if you’d like, but it’s not necessary.
3. Bake the tart shells for 15 to 17 minutes, or until they are crisp and golden blonde. Just keep an eye on them as they bake. Let the shells cool completely before removing them from the pans.

Assemble Pastry Cream Tartlets

1. Place 2 – 3 tablespoons chocolate ganache on the bottom of each tart shell. Spread it to the edges. Add spoonfuls of cooled pastry cream directly over ganache, completely filling the tartlets. 
2. Add remaining ganache to a small bowl. With a hand mixer, beat it on medium speed until light and fluffy (about 4 to 5 minutes).
3. Transfer the whipped ganache to a piping bag fitted with a metal tip. Pipe decorative touches over the surface of the pastry cream tartlets. Or if desired, garnish with chocolate shavings, chocolate sprinkles, or mini chocolate chips.

Serving/Storing Tartlets: Serve the tarts immediately, or store at a cool room temperature for up to 4 ours. Do not assemble and store pastry cream tartlets overnight as the flaky crusts will become soggy.