Preheat your oven to 375°F (190°C). Grease a baking sheet or line it with parchment.

In a saucepan, combine ½ cup water, ½ cup unsalted butter, 1 tablespoon sugar, and a pinch of salt. Bring to a boil.

Remove from heat and stir in 1 cup all-purpose flour until a smooth dough forms. Return to low heat briefly while stirring.

Let the dough cool for 3–5 minutes, then add 4 large eggs one at a time, mixing well after each.

Divide the dough in half and spread one half evenly onto the prepared baking sheet.

Spread the remaining half onto a second baking sheet or bake sequentially.

Bake in the preheated oven for 20–25 minutes or until golden brown. Let cool on a wire rack.

Combine 2 cups milk, ½ cup sugar, and 3 tablespoons cornstarch in a saucepan.

In a separate bowl, whisk together 4 egg yolks and 1 teaspoon vanilla extract until smooth.

Gradually add the hot milk mixture to the egg yolks, whisking constantly. Pour back into the saucepan.

Cook over medium heat, stirring constantly until the mixture thickens. Remove from heat and stir in 2 tablespoons unsalted butter.

Place one cooled pastry layer on a serving platter. Spread custard filling evenly over it.

Top with the second pastry layer. Dust with powdered sugar before serving.