Turn the oven to preheat at 190°C.
Heat up the skillet over medium heat, then add the olive oil and the diced sausages. Stir well for one minute.
Add the sliced bell pepper and the cherry tomatoes, stir from time to time.
In a bowl, whisk the eggs, spring onions and the milk, season with salt and pepper to taste, then pour in the skillet over the vegetables and sausages. Turn the heat to low.
Add on top the diced mozzarella and the sliced olives. Season with freshly ground pepper to taste. Put the lid on and cook for 5 minutes on low heat.
Take off the lid and insert the skillet in the oven. Cook for 12minutes or until the eggs are firmly set on the top.
Take out, leave to cool for 2 minutes then serve. Enjoy!