Preheat the oven to 425°F. Line the muffin tray with paper liners or grease the inside and tops of the tins with a neutral cooking oil.
In a large bowl, whisk together the flour, baking powder, baking soda, salt, sugar, and grated zucchini.
In a small bowl toss the blueberries with 1-2 tablespoons of the flour mixture. Set aside.
Whisk together the eggs, buttermilk, and vanilla extract. Slowly fold into the dry ingredients until JUST combined. Then fold in the blueberries.
Divide the batter equally into the 12 muffin tins and sprinkle on the sugar in the raw. Bake in the preheated oven for 5 minutes, then reduce the heat to 375°F and cook another 13-15 minutes or until a toothpick inserted in the center comes out clean. Let cool 10-15 minutes before eating.