Preheat waffle iron and read manufacturer's instructions. Melt butter in microwave. In a large bowl, combine flour, baking powder, baking soda, cinnamon, salt and sugar. In another bowl, beat together yogurt, milk and egg. Whisk liquid mixture into dry ingredients until just combined. Fold in frozen berries. Stir in melted butter. Brush hot waffle iron with butter or spray. Spoon about 1/2 cup of batter onto iron, smooth out with back of spoon and close to cook. This first waffle will be the tester. Cook waffle until golden brown. Remove to plate and keep warm. Serve with butter, maple syrup or blueberry syrup.
Recipe Courtesy of Food Network Kitchens