Preheat the oven to 350. Butter or grease a loaf pan.
Mix the dry ingredients together in a large bowl. In a small/medium bowl, mix together the wet ingredients.
Add the wet ingredients to the dry, and mix until just combined.
Pour the batter into the prepared loaf pan, and bake in the preheated oven for 40-45 minutes, until an inserted toothpick comes out clean.
To make the glaze, in a small saucepan, melt the butter over medium heat. Add in the brown sugar and stir until sugar has dissolved. Watch the pan carefully, as butter and sugar can turn on you quickly and burn.
Add the milk, and bring to a boil slowly, and boil for about 2 minutes.
Remove from heat, and stir in the vanilla and bourbon. Pour over the apple cake. The glaze will firm up as it cools.