Preheat the oven to 350 degrees. Spray a donut pan with nonstick.
In a large bowl whisk together the flour, sugar, baking powder and salt. In a medium bowl whisk together the eggs, buttermilk, canola oil and vanilla. Add the wet ingredients to the dry and stir until combined.
Scoop batter into the prepare donut pan, filling each cavity ¾ of the way full.
Bake for 12 minutes, then remove from the oven and let donuts sit in the pan for 2-3 minutes.
Combine cinnamon and sugar together in a bowl. Remove donuts from the pan and toss in the cinnamon sugar until coated.
Donuts are best enjoyed same day but will keep in a sealed container for 2-3 days.
Notes
If you don't have buttermilk on hand, use 1 cup of milk and 1 tablespoon of vinegar. Let sit 5 minutes before adding to the recipe. No donut pan? Use a mini muffin pan and make donut holes instead.