Sauté: Heat olive oil in a non-stick skillet over medium heat. Add mushrooms and peppers. Sauté for 3–4 minutes until softened and moisture is gone. Stir in spinach until wilted. Remove veggies from pan and set aside.
Whisk: In a bowl, whisk eggs with a pinch of salt and pepper until fully combined.
Cook: Wipe the skillet clean, add a drop of oil if needed, and pour in eggs. Let them sit for 30 seconds.
Tilt: Use a spatula to lift edges, tilting the pan to let the runny egg reach the surface.
Fill: Once the top is set, spread the cooked veggies and cheese over one half.
Fold: Fold the omelette in half. Turn off the heat and let it sit for 30 seconds to melt the cheese.
Serve: Slide onto a plate and enjoy immediately.