Preheat Oven to 325 Degrees F.
Combine dry ingredients in medium mixing bowl and stir well.
In a separate bowl (or in stand mixer) combine buttermilk, sour cream, oil, egg and vanilla. Mix well to combine.
Add dry ingredient into wet ingredients and mix well. Do not over mix, just until well combined.
Fill reservoirs in a six count donut pan. It works well to put your donut batter into a large zipper freezer bag, clip off a corner and pipe the batter in. If you do not have a donut pan, you could make these in a muffin pan.
Bake for 18-22 minutes or until a toothpick inserted in donut comes out clean and they spring back when lightly touched.