In a medium saucepan, combine milk, sugar, egg yolks, cornstarch, and vanilla over medium heat. Whisk continuously for about 5-7 minutes until the mixture thickens and bubbles gently. Remove from heat, transfer to a bowl, and cover with plastic wrap. Cool to room temperature, then refrigerate for at least 30 minutes.

In a large mixing bowl, cream together softened butter, granulated sugar, and brown sugar until light and fluffy, about 3-4 minutes. Add the eggs one at a time, mixing well after each addition, followed by the vanilla bean paste. Gradually incorporate the all-purpose flour and baking soda until the dough is just combined, ensuring not to overmix.

Wrap the dough in plastic and refrigerate for at least 30 minutes.

Preheat your oven to 350°F (175°C). Scoop the chilled dough and form tablespoon-sized balls on a parchment-lined baking sheet, spaced a couple of inches apart.

Bake the cookies for 9-11 minutes until lightly golden around the edges. Allow to cool on the sheet for a few minutes before transferring to a wire rack.

Once cool, create a small well in each cookie and fill with the chilled pastry cream.

Sprinkle a thin layer of granulated sugar over the filling. Using a kitchen torch, caramelize the sugar until golden brown and bubbly.