Heat 2 cups of whole milk over medium heat until steaming but not boiling. In a bowl, whisk 4 egg yolks, ½ cup granulated sugar, a pinch of salt, 2 teaspoons vanilla bean paste, and 2 tablespoons cornstarch until smooth. Gradually mix into the hot milk. Cook over low heat for 8-12 minutes until thickened. Stir in 2 tablespoons unsalted butter, cover, and refrigerate until cool.

Preheat oven to 350°F (175°C). Line two baking sheets with parchment paper. Whisk 2 cups flour, 1 teaspoon baking powder, and a pinch of salt together. In a bowl, cream ½ cup unsalted butter and 1 cup sugar until fluffy. Beat in 1 egg and 1 teaspoon vanilla bean paste, then mix in dry ingredients until just combined.

Portion dough with a cookie scoop, roll into balls, and coat in granulated sugar. Flatten each ball slightly with your palm to create circular discs.

Bake cookies for 9-10 minutes until edges are golden and centers underbaked for chewiness. Cool on baking sheets for 5 minutes, then transfer to wire racks.

Once cooled, dollop or pipe chilled pastry cream onto the center of each cookie. Sprinkle a thin layer of granulated sugar over the cream for a brûlée finish.

Using a kitchen torch, caramelize the sugar on top until golden brown. If using a broiler, monitor closely to prevent burning. Allow to cool before serving.