Preheat the oven to 375°F. Coat a donut pan in butter or nonstick cooking spray.
In a large mixing bowl, mix flour, baking powder, baking soda, and salt until combined. Set aside.
Cream together the butter, oil, sugar, brown sugar, and vanilla until smooth in a medium-sized mixing bowl.
Beat the eggs into the butter mixture.
Stir the dry mixture into the wet mixture, alternating with the milk until just combined. Do not overmix.
Pour the mixture into a large piping bag or ziploc bag with one corner of the bag snipped off and pipe the batter into each donut cavity about 3/4 full.
Bake in the preheated oven for 8-10 minutes, or until the donuts are cooked through and a toothpick inserted in the donut comes out clean.
Allow the donuts to cool in the pan for 5-10 minutes before removing from the pan.
Mix glaze ingredients together in a medium bowl until smooth.
Dip donuts into the glaze mixture (I like to double dip for an extra thick coat).
Transfer coated donuts to a wire rack to cool completely and the glaze to set.