Heat a frying pan over medium heat and cook the bacon until crispy. Remove and set aside.

In the same pan, add butter and cook the mushrooms until soft and golden. Remove and set aside with the bacon.

Whisk the eggs in a bowl and season with salt and pepper.

Pour the eggs into the pan, tilting it to spread them evenly. Cook on low heat until the edges start to set.

Sprinkle cheese, bacon, and mushrooms over one side of the omelette. Let cook until the cheese melts and the eggs are just set.

Carefully fold the omelette in half, slide it onto a plate, and enjoy hot.