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Mushroom Swiss Whopper-Style Burger

Mushroom Swiss Whopper-Style Burger

Elenor Craig
Inspired by the iconic fast-food favorite, this chef-crafted take on the Burger King Mushroom Swiss Whopper leans into deep umami, silky sautéed mushrooms, and melty Swiss over a flame-kissed beef patty. It’s a refined, at-home copycat that keeps the spirit of the original—savory mushrooms, creamy sauce, and that unmistakable grill character—while elevating texture and balance for a truly memorable bite.
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Prep Time 20 minutes
Cook Time 18 minutes
Total Time 38 minutes
Course Main Course
Cuisine American
Servings 4 burgers
Calories 916 kcal

Ingredients
 
 

For the Mushroom Sauce:

  • 12 oz cremini mushrooms, sliced 1/4 inch choose firm, dry mushrooms for best browning
  • 2 tbsp unsalted butter high-quality European-style butter melts silkier
  • 1 tbsp extra-virgin olive oil helps prevent the butter from scorching
  • 1 small shallot, minced or 1/4 small yellow onion, finely minced
  • 2 cloves garlic, minced freshly minced for best aroma
  • 2 tsp Worcestershire sauce Lea & Perrins recommended for classic flavor
  • 1 tsp soy sauce adds savory depth; use low-sodium if preferred
  • ½ cup beef stock use a rich, low-sodium stock to control seasoning
  • 2 tbsp dry sherry optional but recommended; sub with dry white wine
  • 1 tsp fresh thyme leaves, chopped or 1/2 tsp dried thyme
  • 1 tsp cornstarch for slurry
  • 2 tsp cold water for slurry
  • 2 tbsp heavy cream optional; for a silky finish
  • ¼ tsp freshly ground black pepper to taste

For the Burgers & Buns:

  • 1.25 lb ground chuck (80/20) 80/20 for juiciness; divide into four 5-oz portions
  • 1.5 tsp kosher salt Diamond Crystal preferred; season just before cooking
  • 1 tsp freshly ground black pepper adjust to taste
  • 1 tbsp neutral oil for skillet method; use canola or avocado oil
  • 4 pieces sesame seed burger buns, split large, Whopper-style buns
  • 2 tbsp unsalted butter, softened for toasting buns
  • 8 slices Swiss cheese Baby Swiss or Emmentaler melt beautifully; 2 slices per burger

For the Assembly:

  • ½ cup mayonnaise Duke’s or Hellmann’s for classic tang
  • 1 tsp Dijon mustard optional; whisk into mayonnaise for a subtle lift
  • 1 tbsp flat-leaf parsley, finely chopped optional garnish for freshness

Instructions
 

  • Prepare the Mushroom Sauce (10 minutes): In a large skillet over medium-high heat, add the butter and olive oil. When the butter foams, add the sliced cremini mushrooms in an even layer. Cook without stirring for 3–4 minutes, then stir and continue to sauté until deeply browned and glossy, about 3 more minutes. Add the minced shallot and garlic; cook until fragrant, 45–60 seconds. Deglaze with dry sherry, scraping up browned bits. Stir in Worcestershire, soy, thyme, and beef stock. Simmer briskly until slightly reduced, about 2 minutes. Whisk cornstarch with cold water, drizzle into the pan, and simmer 30–60 seconds until the sauce lightly coats the back of a spoon. Off heat, swirl in heavy cream (optional). Season with black pepper and adjust salt if needed. Keep warm on low.
  • Toast the Buns (2 minutes): Spread the cut sides of the sesame buns with softened butter. Toast cut-side down in a dry skillet over medium heat until golden, about 1–2 minutes, or place briefly under a preheated broiler at 450°F (232°C) watching closely to avoid scorching. Set aside.
  • Form the Patties: Divide ground chuck into four equal 5-oz portions. Gently form wide, thin patties about 4.5–5 inches across with a slight rim and a shallow dimple in the center to prevent puffing. Avoid overworking for tenderness.
  • Preheat and Season: Preheat a gas/charcoal grill to high heat (about 500°F / 260°C) for that flame-kissed note, or heat a cast-iron skillet over medium-high until lightly smoking (surface ~400°F / 205°C). Season patties generously on both sides with kosher salt and black pepper just before cooking.
  • Cook the Patties (6 minutes): Grill or sear the patties for 3 minutes on the first side until the edges look browned and beads of juice appear on top. Flip, top each with 2 slices of Swiss, and cook another 3 minutes, closing the grill lid or tenting the skillet to encourage melting. Aim for about 135°F (57°C) internal for medium; cook longer to your preference. For well-done per USDA safety, 160°F (71°C).
  • Sauce Consistency Check: If the mushroom sauce has thickened too much, loosen with a splash of warm stock; if too thin, simmer briefly to concentrate. It should be spoonable and glossy, not runny.
  • Assemble: Stir Dijon into the mayonnaise (optional), then spread on both bun halves. Place the cheesy patty on the bottom bun, spoon a generous layer of warm mushrooms and sauce over the top, sprinkle with parsley (optional), and cap with the top bun. Serve immediately—the aromas should be buttery, toasty, and savory with a hint of sherry and thyme.

Notes

Chef’s Tips:

  • For deeper browning, avoid crowding the mushrooms; cook in two batches if needed.
  • Cheese Melt Insurance: If using a skillet, add 1 tsp water and cover for 20–30 seconds to steam-melt the Swiss.
  • No Sherry? Use a splash of apple cider vinegar plus 1/2 tsp sugar to mimic brightness and roundness.
  • Beef Swap: 50/50 chuck and brisket blend boosts beefiness. For leaner, use 85/15 and add 1 tsp beef tallow to the skillet.
  • Dietary Tweaks: Use gluten-free buns and tamari for a GF version; substitute a thick grilled portobello cap for the patty to go vegetarian, keeping the same sauce.
  • Grill Lines: Rotate patties 90° halfway through each side if you want classic crosshatch marks.

Nutrition

Calories: 916kcalCarbohydrates: 9gProtein: 37gFat: 81gSaturated Fat: 30gPolyunsaturated Fat: 16gMonounsaturated Fat: 28gTrans Fat: 2gCholesterol: 183mgSodium: 1376mgPotassium: 945mgFiber: 1gSugar: 3gVitamin A: 876IUVitamin C: 4mgCalcium: 372mgIron: 4mg
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