Mixed Berry Streusel Muffins

Preheat oven to 400°F and line a muffin tin with paper liners. In a small bowl, combine the streusel topping ingredients until crumbly. Set aside.

In a large bowl, whisk together the flour, light brown sugar, baking powder, salt, and cinnamon.

In a separate bowl, combine the eggs, milk, vanilla, vegetable oil, and sour cream. Add the wet ingredients to the dry ingredients, stirring until just combined. Be careful not to over stir.

Gently fold in the frozen berries until evenly distributed throughout the batter.

Spoon the batter into the muffin cups, filling each about two-thirds full. Sprinkle the streusel topping over each muffin. Bake for 24-28 minutes or until a toothpick inserted into the center comes out clean.

Allow the muffins to cool in the tin for 5 about minutes before transferring them to a wire rack to cool completely.