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

Cream together softened unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes.

Add the large egg and vanilla extract, mixing until fully blended and smooth.

Sift together all-purpose flour, baking soda, salt, ground cinnamon, and nutmeg in a separate bowl.

Gradually mix the dry ingredients into the wet mixture until a soft dough forms.

Form small balls of dough about 1 inch in diameter and flatten slightly on the baking sheet, leaving space between each cookie.

Bake for 10-12 minutes until edges are golden and centers are set.

Cool cookies on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.

Simmer heavy cream in a saucepan until bubbling, then whisk in brown sugar and cornstarch until dissolved.

Allow the cream mixture to cool until it thickens slightly.

Spoon the cream mixture onto each cookie and broil for 1-2 minutes until caramelized.

Cool for a few minutes before serving to ensure the topping sets slightly.