Mixed Berry Streusel Muffins

Name: Mixed Berry Streusel Muffins
Ingredients: 3 1/2 cups all-purpose flour; 1 cup granulated sugar; 1/2 cup brown sugar; 4 1/2 teaspoons baking powder; 1 teaspoon baking soda; 1 teaspoon kosher salt; 2 cups buttermilk; 1 stick unsalted butter, melted ((8 tablespoons)); zest of 1 lemon; 2 large eggs; 2 cups assorted berries (I used 1 cup blueberries & 1 cup raspberries); 3/4 cup all purpose flour; 1 teaspoon ground cinnamon; 1/4 teaspoon salt; 4 tablespoons unsalted butter (cut into small cubes)