Preheat oven to 425 F. Grease 15 donut tins in donut pans.
In a large bowl, beat butter, oil, and sugars together until well-combined.
Mix in eggs and vanilla.
Beat in milk until combined.
Stir in flour, baking powder, baking soda, and salt until combined.
Spoon or pipe batter into prepared pans.
Bake for 9-15 minutes, or until donuts spring back when lightly touched.
Let cool in pan for 5 minutes.
Brush lightly with melted butter.
Combine cinnamon and sugar in a plastic bag.
Add donut, and gently shake to coat in cinnamon sugar.
*The topping amounts will make lightly coated donuts. If you'd like a heavier coating, like the donuts pictured, double or triple the topping amounts. **I drizzle the donuts with cajeta, which is similar to dulce de leche. It's optional but definitely delicious. ***Recipe nutrition facts are estimates.