Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9x13-inch baking dish.
Bring a large pot of lightly salted water to a boil. Add elbow macaroni and vegetable oil to the boiling water and cook, stirring occasionally, until cooked through but firm to the bite, 8 to 10 minutes. Drain and return pasta to the pot. Stir 1/2 cup melted butter into macaroni.
Heat olive oil in a skillet over medium-high heat. Saute onion in hot oil until tender and translucent, 3 to 7 minutes.
Stir blue cheese, Muenster cheese, Cheddar cheese, and Monterey Jack cheese together in a large bowl. Whisk sauteed onion, half-and-half, eggs, Worcestershire sauce, salt, and black pepper together in another bowl.
Mix 3 1/2 cups of the cheese mixture, half-and-half mixture, and processed cheese food into macaroni. Pour macaroni mixture into the prepared baking dish. Sprinkle remaining cheese mixture over the top and dot with 1 tablespoon butter.
Bake in the preheated oven until hot and bubbling around the edges, about 35 minutes.
