Spray the muffin tin or use cupcake papers.

In a small bowl, add the flour, baking powder and salt and blueberries and mix and set aside.

In a large bowl, add the egg and whisk.

Add the sugar into the egg and mix.

Next, add the butter (be sure it is cooled and not hot) and mix into the egg, lemon juice and sugar.

Add 1/2 the sour cream and mix and then add the remainder and mix.

Pour the dry ingredients into the wet gradually and stirl until incorporated.

Fill the muffin tins to the top of the liners or top of the muffin tin.

Sprinkle on top of each muffin with the granulated/white sugar .