Preheat oven to 425°F and line a muffin pan with liners.
In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and optional cinnamon.
In a large bowl, beat the butter and sugar together on high until combined and fluffy.
Add in eggs one at a time, incorporating fully between each addition.
Add the sour cream and vanilla, and beat until combined.
Pour in the dry ingredients and lightly fold with a rubber spatula or wooden spoon. Do not use an electric mixer to add in dry ingredients!
In a small bowl, toss the blueberries with 1 tbsp of flour.
Gently fold the coated blueberries into the batter.
Pour batter into the muffin tin. The batter will be very thick. You can use a cookie scoop to make it easier.
Bake for 5 minutes. Then, lower the temperature to 375°F for 10-12 minutes, or until the tops are lightly browned and a toothpick inserted into the center comes out clean.
Immediately remove muffins from the pan and enjoy.