Preheat oven to 325 degrees and spray a donut pan with cooking spray.
In a large bowl, whisk together pancake mix and sugar.
In a separate small bowl, lightly whisk eggs. Whisk milk, melted butter, and vanilla into the eggs, until combined.
Stir the wet ingredients into the dry ingredients, taking care not to over-mix. Gently fold in chocolate chips or your add-ins of your choice.
Fill each cavity in donut pan about ¾ of the way with batter. I recommend putting the batter in a plastic bag and cutting off the corner to pipe it into the pan (you can also use a pastry bag).
Bake donuts for 9-11 minutes, until they're light and springy to the touch. Let cool in the pan for a few minutes and then remove to a wire rack to cool completely. If you only have a 6-cavity donut pan, repeat with remaining batter.
When doughnuts are cooled, dip upside down into icing to coat the tops. Add sprinkles or topping of choice.