Preheat the oven at 350º.
In a bowl, sift together flour, salt, baking powder, and sugar. Set aside
In a mixer, combine butter, eggs, vanilla, lemons zest, lemon juice, and milk until well combined.
Add the dry ingredients to wet ingredients in 3 parts.
Coat frozen blueberries with 1 tbs flour, and gently stir together to the mixture.
Scoop the mixture into cupcake liners and bake for 22 minutes.
To make the frosting, combine all the ingredients and mix well in high speed.