Pre-heat oven to 400°F or 204°C (an oven thermometer is recommended to be sure your oven isn't too hot or cool).
In a large bowl, add all dry ingredients and stir to combine.
Add eggs, sour cream, milk, butter, lemon juice, lemon zest and vanilla and stir everything until just combined.
Spray your donut pan generously with non-stick cooking spray. Don't be afraid to overdo it a bit.
Pipe your batter into wells of donut pan with a piping bag or zip-top bag with a corner cut off.
Cook for about 10 minutes or until donuts spring back when touched.
Remove from the oven and let cool in the pan for a few minutes before removing to a wire rack to cool completely.
Meanwhile, mix together your glaze ingredients with a hand mixer in a wide bowl.
When the donuts are cool, dip the tops in the glaze. Top with sprinkles, poppy seeds, or lemon zest.