Preheat the oven to 180 C / Gas 4. Bring a pot of salted water to the boil and cook the macaroni according to the packet instructions; drain. Then put the pasta back into the pan.
In a large bowl, mix the cream cheese with the milk and half of the Cheddar cheese.
Add the cheese mixture to the cooked macaroni, then stir in the sweetcorn and ham.
Place into an ovenproof dish and scatter the remaining cheese over the top.
Bake in the oven until bubbly and golden, about 15 minutes.