1/2cupbutter unsalted, at room temperature and very soft
Heat waffle iron.
In a large bowl, mix together the cornmeal, flour, baking powder, sugar and salt. In another smaller bowl, beat eggs, add milk, yogurt and oil. Pour the yogurt mixture into the dry ingredients and stir until just combined. Fold in the blueberries. Allow batter to sit 5 minutes while waffle iron is heating.
Cook waffles according to your waffle iron instructions. I cooked these waffles in a Belgian waffle iron and it took 4 to 5 minutes for medium browned waffles.
Mix butter and sugar together until smooth. Stir in blueberries and mix until well incorporated. Some berries will break and color the butter. This is okay. Once you have it mixed store in an airtight container in the refrigerator up to 2 weeks.