Take 2 tbsp oil in the pan and add in water heat it to boil macaroni. Drain the water and add the cold water in the macaroni. Add some oil in the macaronis to keep it separated. Take 2 tbsp oil in the pan and add in mushrooms, capsicums, red chilies, green chilies, salt and some black pepper. cook it and then add in macaronis and ½ cup tomato ketchup. Take 1 tbsp butter in a pan and add in 2 tbsp flour in it. Sauté it and remove it from the flame. After 5-10 minutes add in milk and open the flame. Keep on stirring it till the sauce thickens. Then add in grated cheese. Grease the baking dish and add in some white sauce then put the prepared macaroni. Add rest of the prepared white sauce and bake it for 8-10 minutes and serve.