Mushroom, Leek & Sausage Breakfast Casserole Serves 6 Ingredients: 1 tablespoon extra-virgin olive oil 1 small onion, diced 2 leek bulbs (white part), thinly sliced 8 ounces sliced mushrooms 6 ounce bag baby spinach 2 garlic cloves, minced 6 links or 4 patties chicken or …