1.Preheat oven to 350 degrees, spray a donut pan with baking or cooking spray, set aside.
2.In a large mixing bowl, combine all dry ingredients with a whisk. Add in sugar and lemon zest. Whisk again.
3.In a medium bowl, combine butter, egg, sour cream, milk, and vanilla extract.
4.Make a well in the center of large bowl and add in wet ingredients.
5.Using a rubber spatula, gently mix wet into dry but try not to over mix the batter. Dig down to incorporate all dry into wet.
6.Place in a Ziploc bag and squeeze down to one corner and cut the tip off and squeeze into each well. About 2/3 to 3/4 full. Or use a small teaspoon and spoon batter into each donut well.
7.Bake for about 8 to 10 minutes. Donuts should spring back when lightly touched and a toothpick should come out clean or with dry crumbs.
8.Let cool in pan for 10 minutes on a wire rack. Then, invert donuts onto wire rack.
9.While donuts are cooling, prepare the glaze by combining all ingredients with a small whisk. Start with 1 tbsp lemon juice and whisk until smooth.
10.Dunk each donut into glaze and set on wax or parchment paper. When glaze is starting to set up, toss sprinkles over each donut. Let set up completely before serving. Enjoy the lemon love!