Preheat oven to 425 degrees. Spray donut hole pan or muffin tin with cooking spray.
In a medium bowl, sift flour, sugar, baking powder, and salt.
In small bowl, mix together vanilla, buttermilk, egg, and butter until well combined.
Stir wet ingredients into dry ingredients until combined.
Fill each donut hole cup with 1 level tablespoon (3/4 mini muffin cup full if doing muffins).
Bake 7 minutes (9-10 minutes for muffins) or until tops spring back when lightly touched. Remove donut holes from pan to wire rack. Cool completely. Dip in additional melted butter and roll in a cinnamon sugar mixture, in powdered sugar, or in a chocolate or vanilla glaze.
Recipe by Simple, Sweet & Savory at https://www.simplesweetsavory.com/baked-donut-holes/