Step 1

Preheat the oven to 425°F. Lightly spray three 6-cavity donut pans with nonstick cooking spray.

Step 2

In a large bowl, whisk the butter, oil, and sugar together until combined. Add the eggs and vanilla and whisk until well combined.

Step 3

In a separate bowl, add the flours, baking powder, baking soda, salt, and nutmeg. Stir with a whisk to combine.

Step 4

Stir half the flour mixture into the wet ingredients, followed by the buttermilk, then the remaining flour. Stir just until combined after each addition. The batter will be thick.

Step 5

Transfer the batter into a disposable piping bag or zip-top bag with a small corner cut off. Pipe the batter into the prepared donut pans, filling each cavity 2/3 to 3/4 full.

Step 6

Bake for 7-9 minutes, or until donuts spring back when pressed lightly with your fingertip. Set the donuts on a wire rack while you make the glaze.

Step 7

In a medium bowl, combine the confectioners' sugar, milk, and vanilla. Stir until smooth, adding more milk if needed.

Step 8

While they are still warm, dip the donuts into the glaze and set them on a wire rack placed over parchment paper. Enjoy the donuts warm or allow them to cool. The glaze will set as they cool.