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

In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until well combined.

In a large mixing bowl, cream the unsalted butter with ¾ cup of granulated sugar until light and fluffy, about 2-3 minutes. Mix in the egg and vanilla extract until fully combined.

Gradually add the dry ingredient mixture to the creamed butter and sugar, stirring gently until just combined.

Drop rounded dough balls onto the prepared baking sheets, spacing them about 2 inches apart, and gently flatten the tops slightly.

Bake for 10-12 minutes, or until the edges are lightly golden and the centers are set.

Allow the cookies to cool on the baking sheets for about 5 minutes, then transfer them to a wire rack to cool completely.

In a saucepan over medium heat, combine the heavy cream and a split vanilla bean. Heat until simmering and steep the mixture for 10 minutes.

Whisk together the egg yolks and ¼ cup granulated sugar until light and frothy. Slowly temper the warmed cream into the yolks, whisking continuously to prevent curdling.

Return the mixture to the saucepan, cooking over low heat while stirring constantly until thickened, about 5-7 minutes.

Transfer the thickened custard to a bowl and chill in the refrigerator for at least an hour.

Top each cookie with the chilled custard, spreading it evenly.

Sprinkle granulated sugar over the custard toppings and caramelize the sugar with a kitchen torch until golden and bubbly.

Allow the cookies to cool slightly before serving.