Preheat your oven to 350°F. Line a 9×5-inch loaf pan with parchment paper. Peel and cut 1–2 apples into small cubes. Place them in a small bowl and toss with 1 teaspoon cinnamon. Set aside.
In another small bowl, combine ⅓ cup brown sugar with 2 teaspoons cinnamon. Set aside.
In a large mixing bowl, mash 3 overripe bananas until smooth. Add 2 eggs, 1 teaspoon vanilla extract, 5 tablespoons melted butter, ⅓ cup real maple syrup, and ½ cup Greek yogurt. Whisk until well combined.
In a separate bowl, whisk together 1¾ cups all-purpose flour, 1 teaspoon baking soda, and ½ teaspoon kosher salt. Add the dry ingredients to the wet ingredients and gently stir until just combined. Be careful not to overmix; stop stirring as soon as the flour is almost completely incorporated.
Pour half of the banana bread batter into the prepared 9×5-inch loaf pan. Add half of the cinnamon-coated apples over the batter, then sprinkle half of the ⅓ cup brown sugar and 2 teaspoons cinnamon mixture over the apples.
Pour the remaining banana bread batter over the apple layer. Top with the remaining apples and remaining cinnamon sugar mixture.Use a knife or toothpick to gently swirl the apples and cinnamon sugar into the batter. Gently press any apples sitting on top into the batter so they bake into the loaf.
Bake at 350°F for 65–75 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs but no wet batter. If the top starts to brown too quickly, loosely tent the loaf with foil for the remaining baking time.
Allow the banana bread to cool in the pan for at least 10 minutes before carefully removing it and transferring it to a cooling rack.
In a small bowl, whisk together 1 cup powdered sugar and 3 tablespoons milk until smooth. If the glaze is too thick, add a small splash of milk. If it's too thin, add a little more powdered sugar until you reach your desired consistency. Drizzle the glaze over the cooled Apple Fritter Banana Bread. Slice, serve, and enjoy!