Heat the oven to 400°F / 204°C and spray a 15x10 inch baking pan with cooking spray.
In a large pot, cook the spaghetti according to the package instructions, then rinse with cool water and drain.
In a small bowl, whisk milk, eggs, and salt, then pour the mixture over the spaghetti, and mix until combined.
Mix in half of the mozzarella cheese and cheddar cheese until combined.
Now, spread the mixture evenly into the baking pan. Bake in the oven for 15 minutes, then top with the toppings (tomato sauce, the remaining of cheddar cheese and mozzarella cheese, olives and tomatoes) and bake for another 10 minutes or until the cheese melt.
Serve immediately.
Notes
Grease your casserole dish well with oil or butter to ensure the spaghetti base doesn’t stick.