Prepare the Apple Cinnamon Filling
In a small bowl, mix the diced apple with brown sugar and cinnamon. Set aside.
Step 2: Make the Batter
In a mixing bowl, cream the softened butter and sugar until light and fluffy. Add eggs one at a time, beating well after each. Stir in vanilla.
In another bowl, whisk together flour, baking powder, baking soda, and salt. Add the dry mixture to the wet ingredients, alternating with sour cream and milk. Mix just until combined.
Step 3: Layer the Loaf
Preheat oven to
