In a medium saucepan, heat 2 cups of whole milk over medium heat until hot but not boiling.

In a bowl, whisk together 6 egg yolks, ¾ cup granulated white sugar, a pinch of salt, 2 tablespoons of vanilla bean paste, and 3 tablespoons of cornstarch until smooth.

Gradually mix in the heated milk, then return the mixture to the saucepan.

Cook, whisking constantly, until thickened (about 5 minutes). Remove from heat and stir in 2 tablespoons of unsalted butter.

Chill in the fridge while you make the cookie dough.

Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a bowl, whisk together 2 ¼ cups of all-purpose flour, 1 teaspoon of baking powder, and ½ teaspoon of salt.

In a separate large bowl, cream ½ cup of unsalted butter and 1 cup of granulated sugar until light and fluffy, about 3 minutes.

Add in 1 egg and 1 teaspoon of vanilla extract, mixing until well combined.

Gradually incorporate the dry ingredients until just combined.

Using a cookie scoop or your hands, portion out the dough into 1.5-inch balls.

Roll each ball in granulated sugar, ensuring they are well coated.

Place the sugar-coated balls on the prepared baking sheets, leaving space between each for spreading.

Gently flatten each ball with your hand to about ½ inch thick.

Place the cookie sheets in the preheated oven and bake for 9-10 minutes, or until the edges are lightly golden and the centers are still soft.

Once baked, remove them from the oven and allow the cookies to cool on the sheets for 5 minutes.

Transfer the cookies to a wire rack to cool completely.

After the cookies have cooled, pipe the chilled vanilla pastry cream onto the center of half of the cookies.

Top each with another cookie to create a sandwich.

Generously sprinkle granulated sugar over the top of each cookie sandwich.

Using a kitchen torch, carefully caramelize the sugar until it forms a crispy, golden layer on top.

Let the cookies cool briefly before serving.