"We like to save these small amounts of lasagna ingredients when we make a pan of lasagna for dinner. Then we make our omelets a few days later. It keeps us from having to cook such a small amount of sausage or open a whole jar of sauce for only a few ounces. The yumminess of lasagna in a great breakfast form! Serve with garlic toast."
Heat a small skillet over medium-high heat. Cook and stir Italian sausage in hot skillet until browned and crumbly, 4 to 6 minutes. Drain and discard grease.
Melt butter in a skillet over medium heat. Pour eggs into skillet and sprinkle with sausage and Italian seasoning. Cook, occasionally lifting edge with spatula to allow uncooked eggs to flow underneath, until omelet is almost set, 4 to 6 minutes; flip.
Spread ricotta cheese and spaghetti sauce on top of the omelet; cook until omelet is completely set, 3 to 5 minutes. Sprinkle shredded mozzarella cheese over the top, fold in half, and transfer to a plate.