Preheat your oven to 190 degrees C (374 degrees F) and line a baking sheet with parchment paper.

Using a pastry cutter, cut rings from the puff pastry. For half of these rings, cut a smaller hole in the center. Place them on top of the whole rings, pressing gently to adhere.

Arrange the puff pastry rings on the prepared baking sheet.

Whisk the egg yolk with 1 tablespoon milk and brush the tops of the rings.

Bake for about 20 minutes until golden brown, the layers puffed and honeyed.

Allow them to cool completely on a rack so the insides stay crisp.

In a saucepan, heat most of the milk over medium heat until just steaming.

In a bowl, mix the remaining milk with the 3 egg yolks, 50 g sugar, 20 g cornstarch, 15 g flour, and a pinch of salt until smooth.

Gradually pour the hot milk into this egg mixture while stirring constantly to temper.

Return the mixture to the saucepan and cook over medium heat until it thickens, stirring constantly until it coats the back of a spoon.

Remove from heat and stir in 1 tsp vanilla extract and 1 tsp butter until glossy.

Cover the cream with plastic pressed to the surface and allow it to cool fully.

Once cooled, spoon the vanilla cream into each pastry ring.

Pile fresh blueberries on top and dust lightly with powdered sugar before serving.