Grease a large casserole pan with oil or butter.Preheat oven to 400 degrees F.Add oil to a pan and stir in onion. Cook until translucent (about 3 mins)Add in bell pepper and cook for one more minute.Crack eggs into a large mixing bowl. Whisk well.Add in milk and stir.Add in cooked onion and bell peppers, tomatoes, kale, cheese and salt and pepper and stir to combine.Add mixture to casserole pan and bake for 30 mins or until cooked all the way through.Let stand for 10 minutes before cutting in.