Bring a large pot of salted water to a boil. Cook pasta until al dente. Drain and reserve ½ cup pasta water.
In a large skillet over medium heat, cook bacon until crisp. Remove and set aside.
In the same skillet, cook ground beef until browned. Drain excess fat.
Add onion to the beef and cook until softened. Stir in garlic, salt, pepper, garlic powder, and onion powder.
Reduce heat to medium-low. Add milk and cream, stirring gently until smooth.
Gradually stir in cheddar cheese until melted and creamy.
Add cooked pasta and chopped bacon. Toss to coat evenly.
If needed, add reserved pasta water to loosen the sauce.
Remove from heat. Stir in mustard or pickle relish if using. Serve warm.