Preheat oven to 350°F. Lightly grease donut pan(s) with cooking spray. Set aside.
Using a hand mixer or stand mixer with paddle attachment, beat cake mix, eggs, sour cream, and oil in a large bowl until smooth.
Place the batter in a piping bag or large plastic bag (such as ziploc) with the corner cut off and pipe into the prepared donut pan, filling each one about ½ full with batter.
Bake for 12-15 minutes or until the donuts begin to get golden brown and bounce back when tapped gently on the top.
Allow the donuts to cool completely before removing from the donut pan and glazing.