1. Preheat oven to 350ºF.
2. Butter and flour 9x5-inch loaf pan. Set aside.
3. In a small bowl mix 1/2 cup brown sugar, cinnamon and nutmeg. Set aside.
4. In a medium bowl, toss apples with 1 tbsp brown sugar, 1 tbsp granulated sugar, apple pie spice and walnuts. Set aside.
5. In the bowl of a stand mixer with the paddle attachment, cream butter then add 2/3 cup granulated sugar. Beat until light and fluffy, about one minute.
6. With mixer running, add one egg at a time and mix. Scrape bowl and mix for one minute on medium until slightly pale in color.
7. Add vanilla and mix to combine.
8. In a small bowl, mix flour with baking powder and baking soda.
9. With mixer running, alternate adding flour mixture and sour cream. Mix just to combine but to not over mix.
10. Pour half of the batter into the prepared pan and spread to the sides. Add half the apple mixture but pat and poke the apples down into the batter. Sprinkle with half the sugar mixture.
11. Repeat with the rest of the batter, apples and sugar mixture, patting the apples into the batter before topping with the last of the sugar mixture.
12. Bake on center rack of oven for 50 to 60 minutes or until a toothpick inserted into the center of the bread comes out clean. (When checking for doneness insert toothpick into center of bread, making sure your tooth pick is going into batter and not an apple to get a true test for doneness. Ours took exactly 60 minutes.)
13. While cake is baking, prepare glaze by combining brown sugar, butter and cream in a small sauce pan. Heat to a boil and simmer on medium low for two minutes without stirring.
14. Remove from heat and sift in the powdered sugar while you whip. If it lumps, just pass through a small sieve. Let it sit at least ten minutes.
15. Once cake is out of the oven, cool in the pan on a rack for 15 minutes.
16. Loosen sides and flip out of pan and onto the cooling rack, then place the rack over a sheet pan.
17. Drizzle the glaze over the top and let it melt into the warn cake.
18. Serve warm or cool completely.