Preheat the oven to 375°F.
In a large skillet or pot with high sides, cook and crumble the ground beef over medium-high heat for 2 minutes. Add the diced onions and continue cooking for an additional 5 minutes, until the beef is browned and the onions are softened. Drain any excess grease.
Stir in the Manwich sauce, chicken broth, and the undrained diced tomatoes. Bring the mixture to a gentle boil.
Add the uncooked pasta and stir well to ensure it is fully combined. Cover the skillet and allow it to boil gently until the pasta is al dente, stirring occasionally to prevent sticking. Be prepared to cook a few minutes longer than the time specified on the pasta package. Test a noodle to check for doneness before proceeding.
Lower the heat to a simmer. Stir in the corn, then add the cubed Velveeta cheese. Cover the pot and allow the cheese to melt, lifting the cover occasionally to stir until smooth.
Transfer the mixture into a lightly greased 9x13 inch casserole dish.
Sprinkle the shredded cheddar cheese over the top. Cover with foil and bake in the preheated oven for 15 minutes.
Remove the cover and serve hot, ideally with a side of cornbread.