Preheat oven to 350°F (175°C). Grease and flour an 8-inch round cake pan.

In a medium bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, and nutmeg. Set aside.

In a large bowl, beat the butter and sugar together until light and fluffy. Add the eggs, one at a time, then mix in vanilla extract.

Gradually add the dry ingredients to the wet ingredients, alternating with sour cream. Fold in the diced apples.

In a separate bowl, beat the cream cheese, sugar, vanilla, and egg until smooth.

Pour half of the cake batter into the prepared pan. Spread the cream cheese mixture over the batter, then top with the remaining batter.

In another bowl, combine flour, brown sugar, cinnamon, and melted butter to make the streusel. Sprinkle it evenly over the cake.

Bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean.

Let the cake cool before slicing. Enjoy!