1) Preheat oven to 160C/Gas 3.
2) Brush courgettes with olive oil and season with salt and pepper. Griddle over medium heat in a griddle pan until tender and marked. Allow to cool and dice.
3) In a 30 cm cast iron skillet, melt butter over medium high heat. Add pancetta and cook until crisp. Add garlic and allow to cook until fragrant. Stir in the griddled courgette, tomatoes and fresh herbs. Slightly beat egg whites in a large bowl and add to the pan. Turn the heat off, stir in the Swiss cheese and season with coarse salt and 1 teaspoon of black pepper.
4) Place in oven and bake for 25 to 30 minutes or until egg is set.
Remove from the oven and serve.