Preheat the oven to 350°F. Grease a muffin tin or line it with cupcake liners.
In a medium bowl, whisk together the flour, baking soda, salt, cinnamon, and nutmeg.
In a large bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy. Add the egg and vanilla extract, mixing until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the diced apples and nuts, if using.
Scoop about 2 tablespoons of dough into each muffin cup, pressing it down to form a small cup shape.
Bake in the preheated oven for 12-15 minutes or until the edges are golden brown. Remove from the oven and let cool for about 5 minutes.
Carefully remove the cookie cups from the muffin tin and place them on a wire rack to cool completely.
Once cooled, fill each cookie cup with caramel sauce and drizzle additional caramel on top before serving.