Preheat oven to 350 F. Grease and flour an 8x8 baking dish and set aside.
Add butter and brown sugar to the mixing bowl of a stand mixer. Beat on high until light and fluffy. Add in the egg, oil, vanilla extract and beat until combined well. Add in the beer and mix well (it may curdle and that's ok)
Add in the flour, salt, cinnamon, nutmeg and apples. Stir until just combined and pour into prepared baking dish.
Bake for 45-50 minutes. Allow to cool, cut into squares and enjoy with a porter or stout beer.