Start with your prep: thinly slice the mushrooms and grate the cheese.

Melt half the butter in a large non-stick pan and fry the mushrooms over high heat until they release all their moisture and start to caramelize.

Remove them from the pan and set them aside in a bowl, seasoning the mushrooms with salt and pepper.

Separate the eggs into two bowls, ensuring no yolks get into the whites and vice versa. Loosen up the yolks with a fork, then use an electric hand mixer to whip the whites to stiff peaks.

Fold the yolk mix into the whites using large circular motions ensuring no air gets knocked out.

Wipe the pan clean and melt the remaining butter over moderately low heat. Pour in the egg mix and use a spatula to smooth over the surface. Cook on this low heat for 1-2 minutes.

Add the mushrooms and grated cheese onto one half of the omelette and cover the pan securely with a lid or piece of foil. Cook for an additional 1-2 minutes.

Just before serving, use a large spatula to flip the undressed half of the omelette over the half containing filling. Cook for an additional minute, if needed.