Preheat oven to 350° F. Heat olive oil in saute pan over medium heat. Add tomato, potato, sausage and red pepper and cook for 3 minutes. Mix the eggs and milk very well in a bowl; add salt and pepper. Add 2 tablespoons butter to the saute pan. Now add the egg mixture into the pan and scramble for 1 minute. Use remaining 1 tablespoon butter to grease the bottom and sides of 9- x 13-inch baking dish. Pour the semi-scrambled eggs into baking dish and sprinkle cheese over the top. Bake 6 minutes.
Note: To make ahead the night before, simply place the unbaked casserole in the refrigerator overnight. The next morning, bake casserole at 350° F for 40 minutes.