Preheat oven to 350°F (175°C). Spray mini muffin pans with nonstick cooking spray.

In a large bowl, beat together the softened butter and cream cheese until smooth. Mix in the brown sugar until the mixture is creamy. Then, mix in the egg yolk and vanilla extract until combined. Add the baking powder, baking soda, cinnamon, and salt and mix until combined. Gradually mix in the flour until a cookie dough forms. Stir in the diced apples.

Scoop 2-tablespoon balls of dough into each muffin cavity. Press lightly to compact. Bake for 10-15 minutes, or until golden brown around the edges. Let cool in the pan for at least 10 minutes before carefully removing.

Store cooled cookie cups in an airtight container at room temperature for up to 3 days, or freeze for up to one month.

For an extra touch, dust with powdered sugar before serving.