Preheat the oven to 350 degrees. Coat two 8 by 4-inch loaf pans with cooking spray. Set aside.
In a small bowl, mix 1 teaspoon of cinnamon with the brown sugar until well combined. Set aside.
Peel and core the apples after washing them. Then dice them into bite-sized pieces. Place the diced apples in a medium bowl. Pour 2 tablespoons of granulated sugar and the remaining 1 teaspoon of cinnamon over the apples. Mix until the apples are coated in the cinnamon-sugar mixture. Set aside.
In a stand mixer fitted, with a paddle attachment, cream the butter, and the remaining granulated sugar on medium speed, about 1 minute. Beat in the eggs one at a time, mixing well after each addition. Add the vanilla.
Turn the mixer to low. Add the flour to the batter in the standing mixer bowl. Add the baking powder and mix thoroughly, scraping the sides of the bowl periodically with a silicone spatula.
Next, add the milk to the batter in increments to keep the milk from splattering. Mix on medium-low speed until well combined.
In the first loaf pan, pour a quarter of the batter. Next, spread a quarter of the apple mixture on top of the batter and sprinkle it with a quarter of the cinnamon-sugar mixture. Gently swirl the batter, incorporating the cinnamon-sugar mixture and apples into the batter using a butter knife. Pour another quarter of the batter into the pan, followed by apples, and the cinnamon-sugar mixture. Swirl the batter with the butter knife. Set aside.
Repeat step 7 with the remaining batter, apples, and cinnamon-sugar mixture for the second loaf pan. Bake for 65 minutes or until golden brown and insert a toothpick in the center until it comes out clean.
Allow the apple fritter breads to cool in their pans for at least 10-15 minutes. Run a butter knife around the edges of the breads to loosen them from the pans. Then invert the breads onto wire cooling racks and allow them to cool completely.
In a small bowl, whisk together powdered sugar and milk until smooth. Drizzle over the apple fritter bread.
Apple fritter bread recipe yields two 8 in. x 4 in loaves.