Pre-heat oven to 350 degrees. Spray a silicon doughnut pan with cooking spray. Mix all of the dry ingredients in a bowl. Add egg, buttermilk, vanilla and butter. Mix well. Place a pastry bag in a glass to make it stable. Pour batter into the bag and cut off the end when ready to use. Pipe batter into the doughnut pan filling it 3/4 of the way. Bake for 15-20 minutes. Cool on a wire rack. Then repeat with more batter.