Preheat oven to 350 degrees F. Grease a donut pan. I use coconut oil.

In a medium mixing bowl add flour, salt, and baking powder and set aside.

With an electric mixer cream butter and sugar. Add egg and beat until light and fluffy. Add lemon juice and lemon zest and mix again.

Add dry ingredients and milk, alternating, starting, and ending with dry.

Add dough to a piping bag and pipe into a donut pan. Bake for 7-10 minutes until lightly golden on the sides. Remove from oven and allow to cool for 5-10 minutes before removing from pan.

Make the glaze while donuts cool.

To a small saucepan, add blueberries, water, and lemon juice. Bring to a simmer and, stirring frequently, cook until blueberries are soft and Mashable.

Remove from heat and mash or use an emulsifier and purée sauce.

Cool sauce to room temperature and then add to a mixing bowl and mix with icing sugar, starting with half, until desired consistency is achieved.

Dip the bottom of the donuts into the glaze until covered. Top with sprinkles or lemon zest if desired. Leave to set.