Preheat and prep the pan: Heat your oven to 350°F (175°C). Line a 9x5-inch loaf pan with parchment paper, leaving overhang for easy lifting.
Lightly grease the sides and paper.
Mix the topping: In a small bowl, combine 2 tablespoons granulated sugar with 1 teaspoon cinnamon. Set aside.
Prep the apples: Peel, core, and dice apples into small 1/4-inch cubes. Pat dry with a paper towel to remove extra moisture.
Combine dry ingredients: In a medium bowl, whisk 2 cups flour, 2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon salt, and 1 to 2 teaspoons cinnamon (to taste).
Whisk wet ingredients: In a large bowl, whisk 3/4 cup granulated sugar, 1/4 cup brown sugar, 1/2 cup oil, 1/2 cup yogurt or sour cream, 1/4 cup milk, 2 eggs, and 2 teaspoons vanilla until smooth.
Combine batter: Add dry ingredients to wet and stir gently just until no dry streaks remain.
Do not overmix. The batter will be thick.
Fold in apples: Stir in the diced apples and any optional nuts or raisins. Spread the batter evenly in the prepared pan.
Add the cinnamon-sugar top: Sprinkle the cinnamon-sugar mixture evenly over the batter.
Bake: Bake for 55 to 70 minutes, or until a toothpick inserted in the center comes out mostly clean with a few moist crumbs.
If the top browns too quickly, tent loosely with foil during the last 15 minutes.
Cool: Let the loaf cool in the pan for 15 minutes, then lift it out using the parchment. Cool on a wire rack for at least 45 minutes before slicing.
Optional glaze: Whisk 1/2 cup powdered sugar with 1 to 2 teaspoons milk and a pinch of cinnamon until smooth. Drizzle over the cooled loaf.