Preheat your oven to 375°F.
Bring a large pot of salted water to a boil and add the pasta.
Cook the bucatini according to package directions until al dente. Drain and set aside.
In a medium saucepan, combine condensed cheese soup, milk and butter over medium-high heat. Stir frequently until the mixture is heated through and bubbling around the edges (about 10 minutes).
Stir in cooked bucatini noodles until evenly combined.
Transfer the noodle mixture into a 9×13” baking dish that has been lightly greased with non-stick cooking spray.
Bake in a preheated oven for 10 minutes or until the top is bubbly and the cheese is melted.
Remove from the oven and let rest for a few minutes before serving.