Preparation

1. Preheat your oven to 350°F (175°C). Grease a standard loaf pan and optionally line it with parchment paper for easy removal.
2. In one bowl, mix together all the dry ingredients: flour, baking powder, baking soda, salt, and ground cinnamon.
3. In another bowl, whisk together the wet ingredients: eggs, granulated sugar, brown sugar, oil, vanilla extract, and yogurt or sour cream.
4. Stir the wet ingredients into the dry ingredients just until combined; do not overmix.
5. Gently fold in the chopped apples.

Assembly

1. Pour half of the batter into the prepared loaf pan.
2. Sprinkle most of the cinnamon sugar mixture over the batter.
3. Add the remaining batter on top and sprinkle with the remaining cinnamon sugar.
4. Use a knife to make a few loose swirls through the batter to create a ribbon effect.

Baking

1. Bake in the preheated oven for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
2. If the top browns too quickly, loosely cover with foil for the last 10-15 minutes.
3. Let the bread cool in the pan for about 15 minutes, then transfer to a wire rack to cool completely.

Optional Glaze

1. To make the optional cinnamon glaze, whisk together powdered sugar, milk (added slowly), vanilla, and a pinch of cinnamon, then drizzle over cooled bread.