Cream the butter and sugar until light and fluffy. Then add the eggs, one at a time, beating until well combined. Add in the vanilla.
Whisk together the flour, salt, baking powder, and cardamom. Add the lemon zest to the milk. Add the flour and milk mixtures into the butter and sugar mixture alternating between the two.
Fold in the blueberries.
Line a 12 cup standard muffin tin with cupcake liners, and fill with batter. Sprinkle the 3 teaspoons of coarse sugar over the tops of the muffins and bake at 375 degrees for about 30-35 minutes.
Notes
Muffins are easy to make; you don't need too many tips.
Having all the ingredients at room temperature with help ensure an even rise and bake.
Fill the muffin tin 3/4 of the way up to get the perfect muffin dome.
Use the biggest sugar crystals you have for the sugar crust—the bigger the sugar, the more dramatic effect.