Brown ground beef with diced onion; drain excess fat.
Season the beef with burger seasoning, salt, and pepper.
Add Velveeta cheese, let it simmer until melted.
Mix in half of the shredded cheddar until well melted.
Melt butter in a pan and toast the hamburger buns.
Assemble the burger in the following order:
- Shredded cheddar on the bottom bun
- Ground beef with melted cheese
- More shredded cheddar on top
- Shredded lettuce (if using)
Finish with ketchup or preferred seasoning.
Cap with the top bun, and enjoy your delicious, cheesy beef burger!