Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a medium mixing bowl, combine all-purpose flour and powdered sugar, then mix in softened unsalted butter and the egg yolk until coarse crumbs form.

Press the dough mixture into mini tartlet pans, ensuring an even layer that rises up the sides. Prick the bottom with a fork.

Bake in the preheated oven for 15-20 minutes, until golden-brown. Cool completely on a wire rack.

In a saucepan, combine milk, sugar, cornstarch, and vanilla extract over medium heat, whisking constantly until thickened (about 5-7 minutes). Cool to room temperature.

Whip the heavy cream until soft peaks form, then gently fold it into the cooled pastry cream.

Fill each tartlet shell with the creamy mixture, smoothing the tops.

Slice fresh strawberries and arrange them on top of the filled tartlets.

Refrigerate assembled tartlets for at least 30 minutes before serving.