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

In a medium bowl, combine flour, baking soda, cinnamon, nutmeg, and salt. Set aside.

In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.

Add the egg, apple cider, and vanilla extract to the butter mixture; beat until fully combined.

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

Using a cookie scoop, drop rounded tablespoons of the dough onto the prepared baking sheet, spacing them about two inches apart.

Bake in the preheated oven for 10-12 minutes, or until the cookies are lightly golden around the edges.

Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.

Once the cookies are cooled, spread a generous tablespoon of caramel sauce on the flat side of one cookie and sandwich it with another.

Drizzle additional caramel sauce over the assembled whoopie pies before serving, if desired.