1. Preheat oven to 400ºF. Line a 12-cup muffin tin with paper liners or mist with cooking spray. Melt butter in a pan over medium-low heat. Transfer to a medium bowl and let cool.
2. In a bowl, whisk flour, cornmeal, baking powder, baking soda and salt. Whisk sugar and maple syrup in another bowl with butter until smooth. Whisk in yogurt, eggs and maple extract, if desired. Stir butter mixture into flour mixture until just moistened. Fold in cranberries.
3. Divide batter among muffin cups. Bake until muffins are golden and a toothpick inserted into center of a muffin comes out clean, 15 to 18 minutes. Let muffins cool in pan 5 minutes, then turn out onto a rack to cool completely.