To bring the flavor out in the collard greens, you'll need to roast the greens. To do this, first spray a cookie sheet with non-stick oil and then spread chopped collard greens on the shit into a thin layer. Cook for 15 minutes and let cool.
Increase oven to 400 degrees. In medium bowl combine flour, cornmeal, baking powder, salt, cinnamon, nutmeg, sugar and roasted collard greens.
In another medium bowl combine mashed sweet potato, eggs, milk and oil.
Combine your flour mixture and sweet potato mixture into one bowl. Mix well.
Spoon into muffin tins and bake for 13-15 minutes or until a toothpick comes out clean.