Preheat your oven to 350 degrees F. Grease a 9x5 loaf pan with butter or nonstick spray, then press a strip of parchment paper into the bottom and up the two long sides so you have handles for lifting the loaf out later.

Make the apple filling: In a small skillet over medium heat, combine the diced apples, 2 tablespoons brown sugar, and 1 teaspoon cinnamon. Cook for 3 to 4 minutes, stirring occasionally, until the apples just start to soften and the sugar coats them. Remove from heat and let cool while you mix the rest.

Make the cream cheese filling: In a medium bowl, beat the softened cream cheese with a fork or hand whisk until completely smooth, with no lumps at all. Stir in 1/4 cup granulated sugar, 1 egg yolk, and 1/2 teaspoon vanilla. Mix until the filling is creamy and uniform. Set aside.

Make the bread batter: In a large bowl, whisk together the flour, 1/2 cup granulated sugar, baking powder, baking soda, salt, 1 teaspoon cinnamon, and nutmeg. In a separate small bowl, whisk the 2 eggs, sour cream, vegetable oil, and 1 teaspoon vanilla together until smooth. Pour the wet ingredients into the dry ingredients and fold gently with a rubber spatula just until no dry flour streaks remain. The batter will be thick. Fold in the cooled apple mixture.

Layer the batter and cream cheese filling in the pan: Spread half of the apple batter into the bottom of the prepared loaf pan. Spoon all of the cream cheese filling over the batter in an even layer. Spoon the remaining batter on top in large dollops. Run a butter knife through the pan in two or three slow figure-eight motions to swirl the layers together. Do not over-swirl or you will lose the distinct ribbon.

Bake for 55 to 65 minutes. Start checking at 55 minutes by inserting a toothpick into the center of the bread portion, not into a cream cheese pocket. It should come out with just a few moist crumbs. If the top is browning too fast before the center is set, tent a piece of aluminum foil loosely over the pan for the last 15 minutes of baking.

Let the loaf cool in the pan for 15 minutes, then use the parchment handles to lift it onto a wire rack. Let it cool completely before slicing, at least 1 hour. For the cleanest slices with the swirl clearly visible, refrigerate overnight and slice cold with a sharp serrated knife.