These hot roast beef sandwiches with cheddar cheese sauce are so easy to make – the cheese sauce takes only a couple of minutes and is so creamy and smooth.

Hot Roast Beef Sandwiches
About four years ago I shared a recipe for hot roast beef sandwiches and I feel like I should mention them because it’s likely they’ll show up in the “recommended” page thing at the end of the post and you might wonder why I’m sharing something so similar. But here’s the deal – these new-fangled hot roast beef sandwiches are totally different and the main difference is the cheese sauce. The old recipe has an old-fashioned cheese sauce made from a bechamel sauce, but the cheese sauce I’m sharing today, well, it’s a less-than-five-minutes microwave sauce. No flour, butter, or whisking required.
And I thought about replacing the old recipe with the new, but I still like the old way of making cheese sauce so I figured there’s enough room in this blog for two kinds of hot roast beef sandwiches. Did I mention they’re topped with a creamy smooth cheddar cheese sauce?

Microwave Cheddar Cheese Sauce
So let’s talk about that cheese sauce. First, it’s so simple to make you’ll want to start adding a warm and oozy cheese sauce on all your sandwiches. I got the idea from Bon Appetit and their amazing 3-ingredient cheese sauce and rescaled it to work for these sandwiches. It’s the sort of sauce that stays smooth and creamy even after it cools and turns these hot roast beef sandwiches into something sort of like what you might get at a famous fast food restaurant. You know, the one with the horsey sauce? Well, now you can stay home and make an even better version of that drive-through favorite. Pop some curly fries in the oven and you’re all set.
Some Ingredients You’ll Need
- Deli roast beef sliced thin. It really is so much better than what you get in a package, so treat yourself and get some of the good stuff at the deli counter.
- Mayo and creamy horseradish
- Mild cheddar cheese, but feel free to get creative. Any good melting cheese should work well.
- The secret to the cheese sauce is evaporated milk. Look for it in the baking aisle.
- The cheese is tossed with some cornstarch which thickens the sauce and keeps the cheese smooth instead of stringy.

More Hot Sandwiches
- Slow Cooker Shredded Beef Sandwiches
- Loaded Pizza Sandwiches
- Grown-Up Sloppy Joes
- Mushroom Spinach Melt

Hot Roast Beef Sandwiches with Cheddar Cheese Sauce
Prep Time: 10 minutes
Cook Time: 5 minutes
Total Time: 15 minutes
Yield: 4 sandwiches 1x
Description
These hot roast beef sandwiches are quick and easy thanks to a simple cheddar cheese sauce (from Bon Appetit) that’s made in the microwave.
Ingredients
Scale
- 1 1/2 tsp creamy horseradish
- 1/4 cup mayonnaise
- 1 cup shredded mild cheddar cheese
- 2 tsp cornstarch
- 1/2 cup evaporated milk
- 1 tbsp butter
- 1/2 pound thin-sliced roast beef
- 4 hamburger buns
Instructions
- Combine the horseradish and mayonnaise in a small bowl.
- Place the shredded cheese in another small bowl and toss it with the cornstarch. Add the evaporated milk and heat it in the microwave for about minute or so until smooth.
- Melt the butter in a skillet and add the roast beef. Cook it for a few minutes until it’s warmed through. If needed heat it again for 30 seconds before you build the sandwiches. Divide the horseradish mayonnaise among the buns (I like it on the bottom bun). Top with the roast beef and cheese sauce. Serve warm.
- Category: Dinner
- Method: Saute
- Cuisine: American
Nutrition
- Serving Size: 1 sandwich
- Calories: 463
- Sugar: 6.4g
- Sodium: 755.4mg
- Fat: 27.5g
- Saturated Fat: 10.2g
- Unsaturated Fat: 15.5g
- Trans Fat: 0.3g
- Carbohydrates: 34g
- Fiber: 1.7g
- Protein: 13.9g
- Cholesterol: 57mg
Keywords: hot roast beef sandwiches, easy cheese sauce
The nutrition information in this recipe is an estimate only and was calculated using Nutrifox, an online nutrition calculator.