Shake Shack Shack Stack Copycat Burger with ’Shroom and ShackSauce

Why You’ll Love This Recipe

• Iconic texture play: a shatter-crisp, cheese-filled ’Shroom atop a juicy, deeply seared smash burger.
• Faithful flavor: tangy, savory ShackSauce and soft potato buns mirror the classic.
• Reliable technique: double-breaded, double-fried mushrooms for a leak-resistant, ultra-crunchy crust.
• Weekend-worthy but doable: clear timings, temperatures, and make-ahead options.

Grocery List

• Produce: 8 large portobello caps, 1 ripe tomato, green leaf lettuce
• Dairy: Muenster, white cheddar, American cheese, unsalted butter, mayonnaise
• Pantry: Potato buns, panko, all-purpose flour, cornstarch, eggs, ketchup, Dijon, dill pickles + brine, garlic powder, paprika, cayenne, kosher salt, black pepper, neutral oil

Full Ingredients

ShackSauce

• 1/2 cup (120 g) mayonnaise
• 1 tablespoon (15 g) ketchup
• 1 tablespoon (15 g) Dijon mustard
• 1 tablespoon (10 g) finely minced dill pickles
• 2 teaspoons (10 ml) dill pickle brine
• 1/4 teaspoon garlic powder
• 1/4 teaspoon sweet paprika
• Pinch cayenne (optional)
• 1/8 teaspoon kosher salt, or to taste

Cheese-Stuffed ’Shroom

• 8 large portobello caps (about 680 g total), stems removed; scrape gills if very dark
• 4 oz (115 g) Muenster cheese, coarsely shredded
• 4 oz (115 g) white cheddar, coarsely shredded
• 1 cup (120 g) all-purpose flour
• 2 tablespoons (16 g) cornstarch
• 1 teaspoon kosher salt
• 1/2 teaspoon black pepper
• 1/2 teaspoon garlic powder
• 3 large eggs, beaten
• 2 cups (100 g) panko breadcrumbs
• 2–3 quarts (1.9–2.8 L) neutral oil for frying (canola/peanut/vegetable)

Smash Burgers

• 1 lb 4 oz (560 g) 80/20 ground beef, divided into four 4 oz (113 g) balls
• 4 slices American cheese
• 1 teaspoon kosher salt
• 1/2 teaspoon freshly ground black pepper
• 1 tablespoon neutral oil or clarified butter (for the griddle)

Assembly

• 4 potato buns (e.g., Martin’s)
• 2 tablespoons unsalted butter, softened
• 4 large leaves green leaf lettuce
• 4 thick tomato slices (about 1/4 in / 6 mm)
• 8 tablespoons (120 ml) ShackSauce (about 2 tbsp per burger)

Step-by-Step Instructions

Step 1: Make ShackSauce and prep the toppings

In a small bowl, whisk together mayonnaise, ketchup, Dijon, minced dill pickles, pickle brine, garlic powder, paprika, cayenne, and salt. Cover and refrigerate for at least 15 minutes to meld flavors. Rinse and dry lettuce leaves and slice tomato into four thick slices. Chill until assembly.

Step 2: Prepare the mushrooms and cheese filling

Wipe portobellos clean with a damp towel. Remove stems and, if very dark, gently scrape the gills with a spoon (optional for a lighter flavor). Pat dry thoroughly—dry mushrooms fry crisper. In a bowl, toss shredded Muenster and cheddar together. Pair caps of similar size. Place about 2 tablespoons (22–25 g) of cheese onto the gill-side of one cap and top with a second cap to form a cheese-filled “sandwich.” Press edges together gently. Repeat to make 4 stacks.

Step 3: Bread the ’Shrooms (double-coat)

Set up three shallow bowls: 1) flour, cornstarch, salt, pepper, and garlic powder; 2) beaten eggs; 3) panko. Working one stack at a time, dredge in the seasoned flour (tap off excess), dip in egg, then press firmly into panko. For a leak-resistant crust, repeat egg then panko for a double coating. Place on a wire rack and refrigerate or freeze for 10 minutes to set the crust.

Step 4: Fry the ’Shrooms to crispy perfection

Heat 2–3 quarts of oil in a deep pot to 350°F (175°C). Fry 2 mushroom stacks at a time for 3–4 minutes, turning once, until deep golden. Transfer to a rack to rest 3 minutes, then return to the oil for a 1–2 minute second fry until mahogany-golden and very crisp. Keep warm in a 200°F (95°C) oven while you cook the burgers. Note: the cheese inside will be molten—handle carefully.

Step 5: Toast the potato buns

Spread about 1/2 tablespoon softened butter on the cut sides of each bun. Toast cut-side down on a hot dry skillet or griddle over medium heat for 1–2 minutes until golden at the edges. Set aside.

Step 6: Smash-sear the burgers and melt the cheese

Preheat a cast-iron skillet or griddle over medium-high heat for 5 minutes. Lightly oil. Season the top of each cold beef ball with salt and pepper. Place onto the hot surface, then immediately press each with a sturdy spatula (use a square of parchment between meat and spatula) to about 1/2 inch (12 mm) thick. Sear without moving for 2 minutes until the edges are deeply browned and lacy. Scrape under the crust, flip, top with American cheese, and cook 45–60 seconds more. Transfer to a warm plate.

Step 7: Build the Shack Stacks

Spread 1 tablespoon ShackSauce on each bottom bun. Top with lettuce and a tomato slice. Add the cheeseburger patty. Crown with a fried, cheese-filled ’Shroom. Spread 1 tablespoon ShackSauce on the underside of each top bun and cap the burgers. Serve immediately and warn guests about the hot melted cheese center.

Pro Tips

• Choose firm, similarly sized portobellos (3.5–4 inches) so they seal evenly and cook at the same rate.
• Double-coating plus a quick chill helps prevent cheese leaks and guarantees a thick, crunchy crust.
• Keep oil at 340–360°F (171–182°C); big temp drops lead to soggy breading. Fry in small batches.
• Smash once—right after the meat hits the griddle—then don’t press again, or you’ll squeeze out juices.
• Use a wire rack (not paper towels) after frying to preserve that crackly crust.

Variations

• Spicy Shack Stack: Add 1 teaspoon hot sauce to the ShackSauce and swap in pepper jack for part of the cheese.
• Air-Fryer ’Shroom: Air-fry at 400°F (205°C) for 7–8 minutes, flip, then 5–6 minutes more until golden. Spray lightly with oil for best color.
• Gluten-Free: Use gluten-free panko and buns; the rest of the recipe is naturally gluten-free.

Storage & Make-Ahead

ShackSauce keeps 7 days refrigerated. Breaded, uncooked ’Shrooms can be covered and refrigerated up to 24 hours, or frozen on a sheet pan, then stored in a freezer bag up to 3 months (fry from frozen, adding 1–2 minutes). Fried ’Shrooms re-crisp in a 400°F (205°C) oven for 8–10 minutes. Cooked burgers are best fresh; if needed, rewarm briefly on a low skillet. Assemble just before serving.

Nutrition (per serving)

Approximate per burger: 980 calories; 48 g protein; 44 g carbohydrates; 68 g fat; 3 g fiber; 1,700 mg sodium. Values will vary with oil absorption, cheese brand, and bun size.