Cook the bacon in a skillet over medium heat until done. Remove the bacon and place on a paper towel to drain the grease. Chop into crumbles; set aside.
Preheat the oven to 325 degrees. Coat the donut baking tray with cooking spray.
Mix the flour, sugar, baking powder, and salt together in a bowl. Add the buttermilk, egg, vanilla, and melted butter. Mix until well combined.
Transfer the batter into a large zip lock bag. Snip off a corner of the bag and pipe the batter evenly into a 6 cup donut pan.
Bake for 9-10 minutes, or until the dough is set and springy (they won't be golden brown). Let them sit for 1-2 minutes then place the donuts on a baking rack to cool a bit.
Meanwhile make the glaze. Combine the powdered sugar, maple extract, cinnamon, maple syrup (optional), and milk together until well combined.
Place some wax paper under the wire rack. Dip the top of the cooled donuts in the glaze then return to the wire rack to allow the glaze to set. Sprinkle the top with bacon crumbles. Enjoy.