Beat eggs in a bowl, and stir in spinach, chopped tomatoes, capsicum, herbs and cheese.
Place skillet over medium heat and melt butter. Once warm, add in the egg mixture and cook until partially set, about 3 minutes. Flip with a spatula, and continue cooking, 2 to 3 minutes.
Reduce heat to low and continue cooking, 2 to 3 minutes, or until omelette reaches the desired doneness.