Grease your donut pan with butter to prevent the donuts from sticking. Using a mixer, combine all ingredients for the donuts except the blueberries.
Add the donut batter to a pastry bag or a zip lock bag with the end cut off and pipe the batter into the donut pan.
Add the blueberries to the pan individually, pressing them gently into the batter with a toothpick.
Bake the donuts for 8-10 minutes, then dip them in the lemon glaze.
Using a bag to pipe the blueberries into the donut pan makes the process much easier!