Preheat your oven to 400 degrees F. Line 8 cups of a standard muffin tin with paper liners; if not using liners, spray cups with cooking spray.
In a mixing bowl or the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugar until fluffy, about 2 to 3 minutes. Add the egg and mix until incorporated.
In a separate bowl, whisk together the flour, baking soda, baking powder, and salt until well combined.
Alternate adding half of the sour cream to the batter, followed by half of the dry ingredients, mixing well after each addition. Scrape down the sides of the bowl, then repeat with the remaining sour cream and dry ingredients until just incorporated. Mix in vanilla extract.
In a small bowl, whisk together the granulated sugar and ground cinnamon.
Dollop a small spoonful of batter into the bottom of each muffin cup and spread out slightly. Fold the blueberries into the remaining batter, then divide between muffin cups (you'll end up with about 1/4 cup of batter total per cup).
Sprinkle tops generously with the cinnamon sugar.
Bake for 7 minutes, then reduce oven temperature to 375 degrees F and bake for 7 to 9 minutes more or until the tops are cracked and golden brown, and a toothpick inserted near the center comes out clean.
Place the pan on a wire rack to cool. Run a knife around the edge to release any stuck-on bits, then gently twist the muffin to release the sides and bottom before removing from the pan. Enjoy warm or at room temperature!
