Spray muffin tin with nonstick cooking spray. In large bowl, rub sugar and lemon zest together with your fingertips until the sugar is moist and the fragrance of lemon is strong.
Whisk in the flour, baking powder, baking soda, and salt. In another bowl, whisk the sour cream, eggs, vanilla, lemon juice and melted butter together until well blended.
Pour the liquid ingredients over the dry ingredients and gently stir to blend. Do not over stir!
Fill the muffin tin half full with better. Place 1-½ teaspoons blueberry jam in center of each muffin cup.
Divide the remaining batter evenly among the muffin cups over top of the jam.
Bake 18-20 minutes. Transfer pan to a cooling rack. Cool 5 minutes then remove from pan. Cool completely, then glaze with icing.