In a large skillet over medium heat brown the ground beef seasoned with salt, chili powder, cumin and garlic powder. Remove meat from skillet and set aside.
Make the roux to thicken your sauce by melting butter in skillet over medium heat and add the flour. Stir with whisk and continue to cook for 2 minutes. Whisk in milk and continue to cook on low for 3-4 minutes until thickened.
Whisk in the cheeses until smooth. Add the salsa and seasoned, browned beef (with accumulated juices). Simmer on low for 5 minutes.
Serve warm with tortilla chips and garnish with chopped cilantro and crumbled Cotija cheese.