Preheat the oven to 350 degrees Fahrenheit. Grease and flour an 8.5 x 4.5 inch loaf pan.
In a medium mixing bowl, whisk together the flour, baking powder and salt. Set aside.
Using an electric handheld or stand mixer fitted with the paddle attachment, beat the butter, sugar and vanilla together, on medium-high speed until smooth and pale (about 3-4 minutes). Scrape down the sides and the bottom of the bowl with a rubber spatula as needed.
Beat in the eggs, one at a time, until incorporated.
With the mixer on low speed, add about half of the flour mixture, alternating with half the milk. Add the remaining flour mixture and milk and mix to combine.
In a mixing bowl, combine the brown sugar, ground cinnamon and apples. Set aside.
To make the topping, in a small bowl combine the brown sugar and cinnamon. Set aside
Pour half of the batter into the prepared loaf pan and top it with half of the apple mixture. With a knife or skewer, swirl through the batter lightly. Don’t over do it. The bread looks better when it has a beautiful thick layer of fruit and cinnamon sugar in the middle.
Pour the remaining batter on top and then the remaining apple mixture. With a knife or skewer, swirl through the batter a couple of times in both directions. Sprinkle the cinnamon sugar mixture on top.
Bake for about 45 to 55 minutes or until a cake tester or toothpick inserted into the center comes out clean. Only a few moist crumbs should attached to the cake tester or toothpick due to the soft apples in the center.
Remove the bread from the oven and allow it to cool in the pan for about 15 - 20 minutes. While the bread is cooling, whisk together the glaze ingredients. Remove the bread from the pan and place it on a cooling rack. Drizzle the glaze over the bread. Let the bread cool completely before slicing.