In a large bowl whisk flour,sugar, cocoa powder, salt, and baking powder

In another bowl whisk together buttermilk, sour cream, egg and vanilla

Combine the buttermilk/egg mixture with flour mixture and whisk just until combined

Spoon into donut pans, filling 3/4 full

Bake about 6 minutes for the minis and 7 to 8 minutes for the regular donuts. They will be puffed and spring back when touched

Cool just 1 minute then carefully loosen edges so they will not stick. Remove when cool enough to pull out 3 to 4 minutes and cool on wire racks

In a bowl combine confectioner's sugar, cream and vanilla, whisk until smooth. Add more cream in drops if to thick, it should be a thick but pourable glaze consistancy

Dip tops of donuts in glaze and let dry on wire rack.If you want to decorate them with sprinkles do it right while glazing so the sprinkles will stick