Preheat the oven to 350°F (177°C) and line a 12-count cupcake pan with paper liners.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg. Set aside.
1 1/2 cups (212g) all-purpose flour, 1 1/2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon salt, 1 teaspoon ground cinnamon, 1/4 teaspoon ground nutmeg
In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar until light and fluffy.
1/2 cup salted butter, 3/4 cup (150g) granulated sugar, 1/4 cup (50g) light brown sugar
Add the eggs and vanilla extract, mix until combined.
2 large eggs, 1 teaspoon pure vanilla extract
Alternately add the dry ingredients and milk, beginning and ending with the dry ingredients. Mix just until combined. Do not overmix. Gently fold in the diced apples.
1/2 cup milk, 1 cup peeled and finely diced Granny Smith apple
Fill each cupcake liner about ⅔ full. Bake for 12-14 minutes, or until a toothpick inserted in the center comes out clean.
Remove the cupcakes from the oven and cool completely on a wire rack.