Center a rack in the oven and preheat to 400 F. Spray your muffin pan with nonstick cooking spray or line the cups with paper liners.
In a large bowl, add the sugar and lemon zest. Using a spoon mash together until the sugar is moist and the fragrance of lemon 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, with the whisk or a rubber spatula, gently but quickly stir to combine. Do not over mix the batter – a few lumps are okay.
Mash raspberries slightly and gently fold into batter. Fill muffin cups at least 3/4 of the way. Sprinkle sugar over the top of the batter and bake for 18 to 20 minutes, or until the tops are golden and a toothpick inserted into the center of the muffins comes out clean. Cool for 5 minutes before carefully removing each muffin from its mold. Cool completely on the rack.
Place white chocolate chips in a microwave safe bowl and cook for 30 secs, stir until smooth. Repeat until chips are melted. Drizzle melted white chocolate over muffins. Lets cool, eat and enjoy!