Preheat oven to 350°F. Grease a 12-count muffin tin with nonstick spray or line with paper liners. Set aside.
In a medium bowl, whisk the flour, baking powder, and sugar together.
2 cups all-purpose flour, 1 teaspoon baking powder, ¾ cup granulated sugar
In another bowl, whisk the egg, yogurt, oil, milk, and vanilla together.
1 large egg, ¼ cup Greek yogurt, ⅓ cup vegetable oil, 1 cup milk, 1 teaspoon pure vanilla extract
Pour the wet ingredients to the dry ingredients and mix just until combined.
Gently fold the chopped berries into the batter.
1 cup chopped mixed berries
Use a portion scoop to fill each muffin well with batter, about ⅔ full.
Bake for 20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Let the muffins cool in the pan for 10 minutes, then transfer to a cooling rack.