Preheat oven to 350F.
In a bowl, mix the butter, sugar, and lemon juice.
Incorporate the eggs, buttermilk, blueberries, and add one cup flour and mix well.
Proceed to add the remaining flour and mix until no lumps are left.
Scoop a donut tray with the batter.
Transfer to the oven and bake for about 15 minutes.
To prepare the blueberry glaze, blend the blueberries, cornstarch, and milk.
Pour the mix into a saucepan over low heat, incorporate the sugar, and cook for about 3 minutes (or until the sugar is completely dissolved), set aside to lose heat at room temperature.
Remove from the donut pan from the oven and let them cool down for 5 minutes.
Dip one side of the donuts in the blueberry glaze.
Garnish with the sugar glaze and top with some blueberries.
Serve and enjoy.
