1Heat oven to 400°F. Toss sweet potatoes with oil. Place in single layer on 15x10x1-inch pan.
2Bake 20 to 25 minutes or until tender, stirring after 10 minutes. Cool completely, about 20 minutes.
3Spray 12 regular-size muffin cups with cooking spray. In large bowl, beat eggs, melted butter and milk with whisk until well blended. Add flour, brown sugar, baking powder, sea salt and pepper; stir with spoon just until dry ingredients are moistened. Stir in sweet potatoes, kale and cheeses. Divide batter evenly among muffin cups, filling each about three-fourths full.
4Bake 18 to 22 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes.