Preheat the oven to 375 F.

Line a 12-cup muffin pan with paper liners. Lightly spray the liners and the top of the pan with nonstick cooking spray. Set aside.

Beat the butter with the cream cheese until combined. Scrape the sides and bottom of the bowl and add the lemon zest. Beat until creamy and cohesive (the butter and cream cheese should merge completely). Beat in the salt.

Add the sugar in 2-3 additions, beating well after each addition. Scrape down the sides and bottom of the bowl as needed. Beat just until creamy.

Beat in the eggs, one at a time.

Whisk together the lemon juice, sour cream and vanilla in a measuring cup.

Beat this mixture into the egg-butter-sugar mixture.

Whisk together the flour, baking powder and baking soda in a separate bowl. Add most (reserve about 1/4 cup) of it to the muffin batter. With either a mixer on the lowest speed or a spatula, mix until mostly combined--do not overmix.

Reserve a heaping 1/4-cup of berries. Toss the remainder with the remaining flour mixture. Gently, by hand with a spatula, fold the flour coated blueberries into the muffin batter.

Divide this batter between the muffin wells. Then divide the remaining blueberries to scatter on top of the muffin batter.

Bake for 15-20 minutes, until the muffins are turning golden brown and a cake tester inserted into one of the center muffins comes out clean or with only blueberry juice.

Cool for 5 minutes in the pan before turning out the muffins to finish cooling on a cooling rack. Serve slightly warm or cooled completely.