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

Cream the butter and sugar until light and fluffy, about 3-5 minutes. Beat in the eggs, one at a time.

Whisk together the flour and cornstarch in a separate bowl. Gradually add to the creamed mixture, stirring until just combined.

Drop rounded portions of the dough onto the prepared baking sheet and bake for 12-15 minutes.

In a mixing bowl, whisk heavy cream and vanilla extract until thick and soft peaks form.

Once cooled, fill cookies with a dollop of pastry cream and sandwich with another cookie.

Sprinkle sugar on top of each cookie and caramelize using a kitchen torch or by broiling.

Allow the caramelized tops to cool before serving.