There is so much room for recipe customization there. Crumbled breakfast sausage, chorizo, salsa, cooked veggies (like roasted frozen broccoli) can be subbed in as you see fit. The only two rules are to 1) make sure your filling ingredients are fully cooked before assembling, as the reheat time isn't long enough to cook from raw, and 2) don't overstuff them so that they can't be folded and burst open.