Prep your ingredients. Wipe the mushrooms clean and slice them thin. Finely chop the shallot and herbs. Crack and separate the eggs if using whole eggs, keeping only the whites, or measure out liquid egg whites.

Season the egg whites. In a bowl, whisk the egg whites with a pinch of salt and pepper until frothy. Don’t overdo it; 15–20 seconds is enough to add air and make the omelette fluffy.

Sauté the aromatics. Heat a nonstick skillet (8–10 inches) over medium heat. Add 1 teaspoon olive oil. Cook the shallot for 1 minute until softened. Add garlic and cook 20–30 seconds until fragrant.

Brown the mushrooms. Add mushrooms and a pinch of salt. Cook, stirring occasionally, until they release moisture and take on some color, about 4–6 minutes. If the pan dries out, add a splash of oil or a tablespoon of water to keep things moving.

Add greens if using. If you’re adding spinach, toss in a handful and cook 30–60 seconds until wilted. Taste the mushroom mixture and adjust salt and pepper.

Create the omelette base. Push the mushroom mixture into an even layer. Lower the heat to medium-low. Pour the egg whites over the mushrooms and tilt the pan so the whites spread evenly.

Set the edges. As the edges start to set, use a spatula to gently lift them and let uncooked egg run underneath. This helps the omelette cook through without browning.

Finish with herbs and optional cheese. Sprinkle fresh herbs and, if you like, a teaspoon or two of grated Parmesan or crumbled feta. A light hand keeps it bright and protein-forward.

Fold and steam. When the top is slightly glossy but not liquid, fold the omelette in half. Cover the pan for 20–30 seconds off the heat to finish cooking gently. This keeps it tender, not rubbery.

Plate and brighten. Slide onto a warm plate. Add a squeeze of lemon, a crack of black pepper, and a pinch of red pepper flakes if you like. Serve immediately.