Arby's Mushroom and Swiss Sauce Recipe: Velvety Onion-Chive Blend for Roast Beef

This Arby's Mushroom and Swiss sauce recipe delivers that signature velvety blend you crave with roast beef sandwiches—creamy, tangy, and packed with umami from sautéed mushrooms and melted Swiss cheese.

The professional secret lies in balancing mayonnaise and cream cheese for that signature texture while developing deep flavor through proper cooking technique. What sets this apart is the slow-cooked mushroom base that creates a rich, savory foundation without overpowering the delicate Swiss cheese notes.

The sauce achieves its signature consistency through precise blending and gentle heating—never boiling, which would break the emulsion. I've perfected this method over years of testing, ensuring each batch delivers that restaurant-quality mouthfeel that clings perfectly to roast beef.

The onion and chive addition provides freshness that cuts through the richness, while a touch of mustard adds subtle depth that elevates the entire flavor profile.

What you'll end up with is a velvety sauce that's smooth yet substantial, with visible mushroom chunks suspended in a creamy matrix. This isn't just a sauce—it's the missing piece that transforms simple roast beef into a gourmet experience.

The best part? It keeps beautifully in the refrigerator for up to five days, making it perfect for meal prep or entertaining.

Whether you're recreating Arby's classic sandwich at home or using this versatile sauce on burgers, hot dogs, or even as a dip, the key is maintaining that perfect balance of creaminess and umami. Let's get started on making this restaurant-quality sauce at home with professional results every time.

Ingredients for arby's mushroom and swiss sauce

This velvety blend transforms simple roast beef into a gourmet experience with creamy richness and umami depth.

The mushrooms are the flavor foundation—cremini or baby bella add extra depth, but white buttons work perfectly. Trader Joe's sells pre-sliced mushrooms in a bag, saving time, but slicing your own ensures better texture. For the Swiss cheese, Emmental is ideal, but any mild, shreddable cheese will do. The chives should be fresh—frozen works in a pinch, but they lose their bright flavor once thawed. Mayonnaise and cream cheese are non-negotiable for that signature Arby's texture—full-fat versions create the richest sauce.

No Dijon mustard? Yellow mustard with a pinch of sugar mimics the depth. Substituting Greek yogurt for half the cream cheese gives a lighter texture, but it won't be as velvety. If you're avoiding dairy, vegan mayo and cashew cream work, though the flavor will differ slightly. For extra umami, add 1/2 tsp soy sauce or Worcestershire—just don't overdo it. The olive oil matters here; a fruity, peppery EVOO enhances the mushroom flavor, while a mild oil keeps the focus on the cheese.

This sauce keeps beautifully—5 days in the fridge sealed in an airtight container. For longer storage, freeze in 1-tbsp portions for quick sandwich assembly. The texture thickens when chilled, so stir in 1 tsp milk or water when reheating. Double the batch—it disappears fast on roast beef, burgers, or even as a dip for fries.

Step-by-step instructions for Arby's-style mushroom and Swiss sauce

This velvety blend transforms simple ingredients into a creamy, aromatic sauce perfect for roast beef sandwiches.

Heat the 1 tablespoon extra-virgin olive oil in a medium saucepan over medium heat. Add the 0.5 cup finely diced yellow onion and cook for 3-4 minutes until softened and translucent. Here's where the magic begins—you'll notice the onions release their natural sweetness as they cook down.

Add the 1.5 cups sliced white button mushrooms and cook for another 5-6 minutes until they release their moisture and begin to brown. Stir occasionally to ensure even cooking, and resist the urge to cover the pan—this prevents steaming and helps develop that deep umami flavor. The mushrooms should be tender but still retain some texture, not mushy.

Reduce the heat to low and add the 4 oz room-temperature cream cheese to the pan. Stir constantly with a silicone spatula until it melts completely and blends smoothly with the mushroom mixture. This step is crucial—uneven melting can create lumps that ruin the sauce's silky texture. If the mixture thickens too much, add 1-2 tablespoons of water to loosen it slightly.

Next, stir in the 0.75 cup mayonnaise and 1 tablespoon Dijon mustard. The mayonnaise will help emulsify the sauce, giving it that signature Arby's-style creaminess. The mustard adds a subtle tang that brightens the rich flavors. Mix well until fully combined and smooth, scraping the bottom of the pan to incorporate any browned bits that add depth of flavor.

Add the 0.5 cup shredded Swiss cheese and stir until it melts completely into the sauce. The Swiss cheese contributes a mild, nutty flavor that balances the richness of the cream cheese and mayonnaise. Keep the heat at low to prevent the cheese from separating or burning.

Season generously with the 0.5 teaspoon salt and 0.25 teaspoon freshly ground black pepper. Taste and adjust if needed—this sauce should be seasoned to taste, with a perfect balance of saltiness and subtle peppery heat. The Swiss cheese should be fully melted, and the sauce should be smooth and velvety at this stage.

Remove the pan from heat and stir in the 0.25 cup finely chopped fresh chives. The chives add a bright, fresh finish that cuts through the richness of the sauce. Let the sauce sit for 2-3 minutes to allow the flavors to meld together. The chives will soften slightly but retain their vibrant color and freshness.

For the best results, serve the sauce immediately while it's still warm. It's perfect for drizzling over roast beef sandwiches, melting over grilled cheese, or spooning alongside crispy fries. If you need to reheat leftovers, do so gently over low heat, stirring constantly to prevent separation. This sauce is a game-changer—simple yet deeply satisfying!

Dietary considerations for arby's mushroom and swiss sauce

Dairy-Free Adaptations

For a dairy-free version, replace the cream cheese with 4 oz vegan cream cheese (like Tofutti or Kite Hill) and use vegan mayo (such as Hellmann's Vegan or Just Mayo). Swap the Swiss cheese for ½ cup shredded dairy-free mozzarella or nutritional yeast for a cheesy flavor without dairy.

The texture will be slightly lighter, but the umami from mushrooms and mustard keeps it rich. 🌱

Gluten-Free Considerations

This recipe is naturally gluten-free, but always double-check your mayonnaise and mustard labels for hidden gluten. Brands like Duke's and Primal Kitchen offer certified gluten-free mayo, while Annie's or French's make gluten-free mustard. The mushrooms, onions, and cheese are all gluten-free staples, so no substitutions are needed here.

Lower-Carb Options

To reduce carbs, skip the onions entirely and use 1 cup sliced mushrooms instead. For extra flavor, add 1 tbsp minced garlic when sautéing. The Swiss cheese provides enough richness to balance the sauce without needing the onion's sweetness.

This version keeps carbs under 5g per serving (about ¼ cup sauce).

Nut-Free Safety

This recipe is naturally nut-free, but always verify your cream cheese and mayonnaise brands for cross-contamination warnings. Brands like Philadelphia and Hellmann's are typically nut-free, but facilities may process tree nuts.

For extra caution, use certified nut-free versions of these ingredients. The sauce remains creamy and flavorful without any nut-based components.

Allergen-Friendly Swaps

For egg allergies, use vegan mayo (like Just Mayo) and ensure your cream cheese is egg-free (Kite Hill is a good option). If you're avoiding mustard, omit it entirely or substitute 1 tsp apple cider vinegar for acidity.

The sauce will still deliver that signature tang without relying on allergens. Always check labels for hidden ingredients!

Frequently asked questions