Cut the cherry tomatoes, red pepper and spinach leaves. Melt the butter in the frying pan. Beat the eggs with a fork and season with salt and pepper.
Add the mixture to the pan and spread it out evenly. When it starts to firm up, but still has a bit of raw on top, add grated cheese and also the cherry tomatoes, spinach, and red pepper.
Using a spatula, ease the edges and quickly turn it over onto the other side. The other side will cook a lot quicker, it only needs about 1-2 minutes.
When it is done, place a large plate on top of the pan and flip the omelet as fast as you can.