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

In a large mixing bowl, cream together softened unsalted butter and granulated sugar using an electric mixer until light and fluffy, about 3-5 minutes.

Add the large egg and vanilla extract to the mixture, beating until fully combined, about 1-2 minutes.

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

Gradually add the dry ingredients to the wet mixture, stirring until just combined.

Shape the dough into 1-inch balls and place them onto the prepared baking sheet, flattening each ball into disks about ½ inch thick.

Bake for 10-12 minutes, or until the edges turn golden brown.

Transfer the cookies to a wire rack to cool completely.

In a saucepan, heat heavy cream over medium heat until it simmers. Stir in brown sugar and cornstarch, whisking until thickened, about 3-5 minutes.

Spoon a generous layer of the topping onto each cookie and broil for 1-2 minutes until sugar caramelizes.

Allow the cookies to cool completely before serving.