Creating Apple Pie Cupcakes is straightforward; just follow these steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line a cupcake pan with paper liners.
2. Mix Dry Ingredients: In a medium bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, and nutmeg. Set aside.
3. Cream Butter and Sugar: In a large bowl, beat the softened butter and granulated sugar until light and fluffy, about 3-5 minutes.
4. Add the Eggs: Incorporate the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
5. Combine Wet and Dry Ingredients: Gradually add the dry mixture alternately with buttermilk, starting and ending with the dry ingredients. Mix until just combined; do not over mix.
6. Fold in Apples: Gently fold in the diced apples and nuts if using.
7. Fill Cupcake Liners: Pour the batter evenly into the prepared cupcake liners, filling them about ¾ full.
8. Bake: Bake in the preheated oven for 20-25 minutes or until a toothpick inserted into the center comes out clean.
9. Cool: Remove from the oven and allow to cool in the pan for about 10 minutes before transferring to wire racks to cool completely.
10. Make the Frosting: In a separate bowl, beat the softened butter until creamy. Gradually add the powdered sugar and beat until light and fluffy. Mix in the vanilla extract and adjust the consistency with milk as needed.
11. Frost the Cupcakes: Once the cupcakes are completely cool, frost them generously with the prepared frosting. Optionally sprinkle with cinnamon for an extra touch.