Prepare the tart dough by combining the flour, sugar, and salt in a bowl. Add the cold butter and mix until the mixture resembles coarse crumbs.

Add the egg yolk and cold water, then mix gently until the dough comes together. Shape it into a disk, wrap it, and chill for 30 minutes.

Roll out the chilled dough and cut it to fit the tartlet pans. Press the dough into the pans and trim the edges.

Prick the bottoms with a fork and bake the tart shells until lightly golden. Let them cool completely.

To make the cream filling, heat the milk in a saucepan until warm.

In a separate bowl, whisk the egg yolks, sugar, and cornstarch until smooth.

Slowly add the warm milk while whisking, then return the mixture to the saucepan.

Cook over medium-low heat, stirring constantly, until the cream thickens.

Remove from the heat and stir in the vanilla extract and butter. Let the cream cool completely.

Fill each cooled tart shell with the cream filling.

Arrange the fresh strawberry slices on top of each tartlet.

If desired, brush the strawberries lightly with warmed apricot jam for a glossy finish.

Dust with powdered sugar before serving.