Preheat oven to 350 F.
Spray a 9x5 loaf pan with a non-stick spray.
Mix 1/2 cup of brown sugar and 1 tsp cinnamon together in a bowl, and set aside.
Combine and whisk 1-1/2 cups flour and 1-3/4 tsp baking powder in a separate bowl.
Using a medium-sized bowl, add 2/3 cup granulated sugar and 1/2 cup softened butter, and beat together with an electric mixer until smooth and creamy.
Beat in 2 eggs, one at a time until blended in, then add 1-1/2 tsp vanilla extract and mix in.
Add the flour mixture into the creamed butter mixture and mix until blended.
Mix 1/2 cup milk into the batter and mix until smooth.
Peel 2 large apples, then chop into small pieces, but not too fine. Toss the apples with 2 tbsp granulated sugar, 1 tsp cinnamon and 2 tbsp flour.
Pour 1/2 of the batter into the prepared loaf pan, then add 1/2 the chopped apple mixture.
Sprinkle 1/2 of the brown sugar and cinnamon mixture you set aside earlier on top of the apple layer.
Repeat the layer, adding the remaining batter on top of the apple layer, then top with the remaining apple mixture, and finally the remaining cinnamon and sugar mixture.
Using a knife, swirl through the mixture a few times.
Bake in the oven for about 55 to 60 minutes, until a toothpick inserted into the middle comes out clean.
Allow the loaf to cool for 15 minutes, then remove the loaf from the pan and allow to cool completely on a cooling rack.
Mix 1/2 cup powdered sugar and 1 to 3 tbsp milk together until well mixed, to create a glaze. Once the loaf has cooled, top with the glaze.
