Preheat oven to 350F. Prepare an 8.5x4.5x2.5-inch loaf pan by greasing it with non-stick cooking spray.
In a small mixing bowl, whisk together the brown sugar and 1 teaspoon cinnamon; set aside.
In a large mixing bowl, use an electric mixer to cream together the 2/3 cup granulated sugar and butter until light and fluffy. Beat in the eggs and vanilla, just until combined.
In a small mixing bowl, whisk together the flour and baking powder. Add the flour mixture to the wet mixture and stir until combined. Add the milk and mix until smooth.
Pour half of the batter into the prepared loaf pan and spread out evenly.
In a small mixing bowl, combine the apple filling ingredients. Pour half of the apples over the batter in the pan, then spread on the remaining batter. Top with the remaining apples and press the apples down slightly.
Sprinkle the brown sugar and cinnamon mixture over top of the bread.
Bake at 350F for 1 hour, or until a toothpick inserted into the center comes out clean. Cool in the pan for about 30 minutes.
In a small bowl, combine the glaze ingredients until smooth. Drizzle over the cooled bread.
Slice the bread and serve.