In a medium saucepan, heat 2 cups of whole milk over medium heat until steaming, not boiling. In a separate bowl, whisk together 4 egg yolks, ½ cup of granulated sugar, a pinch of salt, and 2 tablespoons of cornstarch until light and frothy. Gradually pour the hot milk into the egg mixture while whisking continuously to temper the yolks, then return the mixture to the saucepan. Cook on low heat, stirring constantly until thickened and bubbling, about 5–7 minutes. Remove from heat, stir in 2 tablespoons of unsalted butter, and refrigerate until chilled.

Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper. In a bowl, whisk together 2 cups of all-purpose flour, 1 teaspoon of baking powder, and ¼ teaspoon of salt. In a separate large bowl, cream together ½ cup of softened unsalted butter and ¾ cup of granulated sugar until light and fluffy, about 3–4 minutes. Mix in 1 teaspoon of vanilla bean paste and 1 egg, then gradually incorporate the dry ingredients until a soft dough forms.

Using a cookie scoop or spoon, portion the cookie dough into 1-inch balls. Roll each ball in sugar to coat, then gently flatten them between your palms and place them on the prepared baking sheets, spaced a couple of inches apart. Bake the cookies in the preheated oven for 9–10 minutes, until the edges are light golden brown and the centers remain slightly soft. Allow the cookies to cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.

Once the cookies are cool, take the chilled pastry cream and transfer it to a piping bag fitted with a round tip. Pipe a generous dollop of the pastry cream onto the center of each cookie, spreading it just to the edges. For the finishing touch, sprinkle a thin layer of superfine sugar over the pastry cream on each cookie, making sure to cover it evenly for a perfect brûlée crust.

Using a kitchen torch, carefully caramelize the sugar on the tops of each cookie until the sugar melts and turns golden, typically taking 30 seconds to 1 minute. Maintain the torch at a distance to avoid burning the cream beneath. If sugar flames up, gently move the torch away for a moment until it settles, then continue. Allow the cookies to cool for a few minutes to let the caramel harden before serving.