In a saucepan, melt butter over medium-high heat. Whisk in flour and cook for 2-3 minutes until golden. Whisk in milk, season, and refrigerate mixture.
In a large stockpot or Dutch oven, cook ground beef until browned. Season with salt, pepper, and garlic powder. Remove from pot and drain excess fat, leaving 2 tablespoons.
Add onion, potatoes, and red bell pepper to pot. Cook for 10–12 minutes until vegetables are softened. Season with cumin, cayenne, salt, and pepper.
Add corn, black beans, and green chiles to the pot. Return ground beef to pot and stir in broth. Bring to a boil, reduce to simmer, and cook for 15 minutes.
Stir in the prepared roux mixture, then add cubed Velveeta. Cover and cook another 15 minutes, until cheese is melted and soup is thick and creamy.
Serve hot, topped with shredded cheddar and bacon bits if desired.
Notes
For a spicier version, add diced jalapeños or a dash of hot sauce. Freezes well for up to 3 months.