Preheat the oven to 350°F.

Spray a 9 x 5 inch loaf pan with nonstick baking spray. Set aside. 

For the cinnamon sugar, in a small bowl, combine the brown sugar and cinnamon. Set aside. 

For the cake, in a large bowl, using an electric mixer on medium speed, cream the sugar and butter together until light and fluffy. Beat in the vanilla, then add the eggs, one at a time, beating just until each egg is incorporated. Scrape down the sides and bottom of the bowl. 

In a medium bowl, combine the flour, baking powder, baking soda, and salt. Add the dry ingredients
and buttermilk to the butter-sugar mixture in the large bowl, alternating back and forth between the two, starting and ending with our and beating on medium speed. 

Scrape down the sides and bottom of the bowl with a spatula and stir in any unmixed bits of batter. 

5. For the apples, in another medium bowl, combine the sugar and cinnamon. Add the apples and toss until the apples are coated with the cinnamon sugar. 

Add half of the batter to the prepared loaf pan. Add half of the apples in a layer and gently push them down into the batter. Sprinkle half of the cinnamon sugar over the apples. 

Repeat, adding the remaining batter, apples, and cinnamon sugar. Use a skewer to swirl it all together. 

Bake until a toothpick inserted into the center comes out clean, 60 to 65 minutes. 

Mix powdered sugar and cream together in a small bowl until smooth.

Place cake on a serving platter and drizzle warm cake with icing.

Slice and serve warm or at room temperature.