How to Make It
Heat oven to 400° F.
Heat the oil in a medium nonstick ovenproof skillet over medium-high heat. Add the sausage and cook, breaking up with a wooden spoon, until golden, 3 to 5 minutes.
Add the zucchini, onion, and ¾ teaspoon each salt and pepper. Cook, stirring often, until the zucchini is tender, 6 to 8 minutes. Remove from heat and stir in the eggs and Cheddar.
Transfer the skillet to oven and cook until just set, 10 to 13 minutes.
Serve the frittata with salad.