Thick slices of tomato give this healthy breakfast a hint of sweetness.
Top each muffin half with tomato; set aside. In a small nonstick skillet, heat oil over medium-low. Gently crack eggs into skillet; cook until whites are almost set, 1 to 2 minutes.
Top each egg with a slice of cheese; cover skillet for 1 minute. Slide one egg onto each muffin; season with salt and pepper.