Take the eggs, milk and sour cream out of the fridge and allow them to come to room temperature. See above note as to WHY room temperature ingredients are important.This is a good time to sift your flour, baking soda and baking powder. I do this to prevent clumps and evenly distribute the powder and soda. When you don't sift it you can end up with clumps of the powder and soda which is so gross to bite into. If you don't have a fine mesh sifter, you can use a whisk and stir the dry ingredients together really well. .Line a standard sized muffin tin with paper liners. Then lightly spray the top with cooking spray. This will help prevent the muffin tops from sticking to the pan.
Preheat oven to 425°F
Make
Whip the sugars and butter together using a handheld blender or stand mixer with the paddle attachment. Whip until creamed, 2 minutes.
Once Creamed, add the eggs in and mix to incorporate fully. Now add the milk, vanilla and sour cream. Mix to combine. If you're using lemon zest - add it in now.
Toss the blueberries in a bit of the flour. about ½ cup. Hold back a couple tablespoons of blueberries from this to put on top of the muffins once they are in the muffin tin.
Fold in the dry ingredients, stirring until combined but do not mix for many minutes - just be sure its all mixed in and no flour chunks remain and you're good to go. Add in the blueberries. Stir until just combined.
Divide the batter into the paper lined muffin tins. Top the muffins with the remaining blueberries. a couple per muffin.
Bake
Bake for 5 minutes at 425°F then, without taking the muffins out of the oven, turn the oven down to 350°F for 18minutes or until a tooth pick is inserted into the center of a muffin and it comes out with moist crumbs instead of wet batter.total bake time 23 minutes.