01 -
If desired, lightly butter the onion bun and toast until golden.
02 -
Gently warm the sliced roast beef in a skillet over medium heat or use a microwave until just heated through.
03 -
Spread the red ranch sauce evenly over the bottom half of the toasted bun.
04 -
Pile the warmed roast beef onto the sauced bun half, then pour the hot cheese sauce evenly over the beef.
05 -
Cap with the top bun and serve immediately while hot.
06 -
Melt butter in a small saucepan over medium heat. Whisk in flour until combined, then gradually add milk, stirring constantly. Add cheddar cheese and stir until smooth and melted.