Heat oven to 350°F. Line a muffin tray with silicone muffin liners (parchment ones work great too!)
In a large bowl, beat together the eggs, salt, pepper, cumin and chili powder.
Stir in the corn, black beans and cheese.
Add the cooked sweet potatoes (be sure to cool them slightly first!)
Spoon mixture into the prepared muffin tray, you should get 12 muffins.
Bake for 25-30 minutes, until a knife inserted in the center comes out clean.
To re-heat: Heat on top of a paper towel in the microwave for 20-30 seconds.
Freezing instructions: Freeze (short term) in sealed plastic containers. For longer term storage, you may wish to wrap them in plastic first.
Allow to thaw completely, and reheat as described above.