Preheat oven to 375˚F (190˚C). Set aside a 13- x 9-inch (33 x 23 cm) baking dish.
Fill a four-quart (four litre) wide-bottomed pot halfway filled with water, and stir in oil, onion, celery, bell pepper and pasta over medium-high heat until al dente, about eight minutes.
Drain pasta in a colander and transfer to a large bowl.
Add butter and mix to coat pasta. Add evaporated and whole milk, half of the marbled cheddar and Parmigiano-Reggiano and mix.