Prepare the Pasta
Cook the pasta according to package directions until al dente. Drain well and set aside. Be careful not to overcook the pasta as it will continue to cook slightly in the oven.
Cook the Meat Mixture
In a large skillet over medium-high heat, cook the ground beef and diced onion until the meat is browned and the onion is translucent, about 5-7 minutes. Drain any excess grease from the pan.
Combine Ingredients
In a large mixing bowl, combine the cooked pasta with both cans of sloppy joe sauce, stirring until the pasta is well coated. Add the cooked meat mixture and the bag of Velveeta shredded cheese. Mix thoroughly until all ingredients are well incorporated.
Assemble the Casserole
Pour the mixture into a 9x13 inch baking dish, spreading it evenly. Sprinkle the Colby jack cheese over the top, creating a generous cheese layer.
Bake to Perfection
Place the casserole in a preheated 350°F oven and bake for 25 minutes, or until the cheese is melted and bubbly, and the edges are slightly crispy.