Roast Beef Sandwich

Name: Roast Beef Sandwich
Prep time: 5 min
Cook time: 10 min
Total time: 15 min
Cuisine: American
Ingredients: 3 tbsp unsalted butter; 2½ tbsp all-purpose flour; 1¼ cups milk; 1½ tsp Dijon mustard; ½ tsp salt; 6 oz sharp cheddar cheese, shredded; 12–16 oz thinly sliced roast beef; 3 sesame burger buns

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This Roast Beef Sandwich is your answer to diner-level comfort at home—thinly sliced roast beef piled high on a soft sesame bun, draped with a creamy, decadent cheddar cheese sauce. It’s inspired by the classic Arby’s roast beef and cheddar, but made entirely from scratch, with real ingredients and lots of love.

Thick roast beef sandwich piled high with tender sliced beef and creamy cheese sauce on a sesame seed bun

You’re basically wrapping up all your comfort food dreams in one bite: juicy roast beef, a silky cheese sauce, and a bun that soaks up every drop. Serve with curly fries, chips, or a crunchy slaw for a lunch or dinner that feels special but comes together in minutes.

Why You’ll Love This Roast Beef Sandwich

Cheesy and savory. Homemade cheddar cheese sauce is next-level good.
Quick and easy. Ready in about 15 minutes—just assemble and dig in.
Versatile. Add all your favorite toppings or keep it classic and simple.
Perfect for leftovers. A great way to use up extra roast beef from your weekend dinner.

Ingredients You’ll Need

For the Cheddar Cheese Sauce

Unsalted butter: The rich base for your sauce.
All-purpose flour: Helps thicken the cheese sauce.
Milk: Any kind works, but whole milk gives the best texture.
Dijon mustard: Adds tang and depth.
Salt: To round out the flavors.
Sharp cheddar cheese: Shredded from the block for the smoothest melt.

For the Sandwich

Roast beef: Homemade or good-quality deli roast beef, thinly sliced.
Sesame seed burger buns: Or use brioche, potato, or your favorite sandwich roll.

All ingredients for a roast beef sandwich with cheddar cheese sauce laid out: sliced beef, cheese, bread, butter, and seasonings

Ingredient Swaps & Add-Ins

Try other cheeses: Monterey Jack, Swiss, or a blend of sharp cheddar and pepper jack.
Go big on toppings: Lettuce, tomato, red onion, or even a spoonful of horseradish cream.
Different bread: Use ciabatta, sourdough, or even an onion roll.

How to Make a Roast Beef Sandwich

Step 1: Make the Cheese Sauce

In a medium saucepan, melt butter over medium heat. Whisk in flour and cook for about 1 minute, until it forms a smooth paste.

Smooth homemade cheese sauce in a saucepan with a whisk, ready to pour over roast beef sandwiches

Slowly whisk in milk, mustard, and salt. Cook, whisking constantly, until the mixture thickens—about 2–3 minutes.

Finished creamy cheese sauce in a pot, ready to pour over sandwiches or fries

Remove from heat. Add cheese in small handfuls, stirring after each addition until smooth and creamy.

Shredded cheddar cheese being mixed into a pot of sauce for an easy homemade cheese sauce

Smooth and creamy cheddar cheese sauce in a mixing bowl with a whisk

Step 2: Assemble the Sandwiches

Pile thinly sliced roast beef generously onto the bottom bun of each sandwich.

A slice of soft white sandwich bread, perfect for building a deli-style sandwich

Pile of thinly sliced roast beef layered on fresh sandwich bread for a quick homemade lunch

Ladle warm cheddar cheese sauce over the beef (don’t be shy—this is the good stuff).

Open sandwich stacked with roast beef slices and rich cheddar cheese sauce poured on top

Top with the remaining bun and press gently. Serve immediately while the cheese is gooey and melty.

Sesame seed bun filled with thinly sliced roast beef and creamy cheddar cheese sauce, dripping down the sides

Tips for the Best Roast Beef Sandwich

Shred your own cheese. Pre-shredded cheese doesn’t melt as smoothly.
Warm your beef. Heat it gently in a pan or microwave for the best texture.
Toast your buns. For extra flavor and structure, toast the inside of the buns.
Customize it. Load up with veggies or keep it classic—your sandwich, your rules.

Storage & Reheating

Cheese sauce: Store extra sauce in an airtight container in the fridge for up to 4 days. Reheat gently on the stovetop, adding a splash of milk to thin if needed.
Sandwiches: Best assembled and served fresh, but you can keep leftovers wrapped and reheat in a toaster oven or microwave.

Serving Ideas

Serve with curly fries, chips, or a simple side salad.
Pair with homemade coleslaw or pickles for crunch.
Add a side of potato salad or baked beans for a diner-style meal.

Sesame seed bun stacked with sliced roast beef and drizzled with creamy cheddar cheese sauce, served with crispy fries

FAQ

Can I use deli roast beef?

Yes! Go for high-quality, thinly sliced roast beef from the deli for best flavor and texture.

Can I make the cheese sauce ahead?

Definitely. Store it in the fridge and reheat gently, whisking to restore its creamy texture.

What bread works best?

Classic sesame buns, potato rolls, or brioche buns all work beautifully.

Can I add veggies?

Absolutely. Lettuce, tomato, onions, or even a handful of arugula make great additions.