The Shack Stack is a Shake Shack original: a griddled beef patty stacked on top of a panko-fried portobello mushroom cap stuffed with melted Muenster and cheddar. It takes more steps than a regular cheeseburger, but the payoff — crunchy mushroom shell, molten cheese inside, juicy beef on top — is genuinely unlike anything else you can make at home in under an hour.
What makes this version work
Two things matter most here. First, the mushroom prep: you need to scrape out the gills before stuffing. Gills hold moisture, and that moisture turns to steam in the fryer, which can blow out your breading and leave you with a soggy shell instead of a crispy one. Second, the cheese seal. Press the stuffed mushroom firmly closed and freeze it for at least 20 minutes before breading. A cold, firm mushroom holds its shape through the egg wash and panko coating — and through the hot oil. Skip that freeze step and the cheese leaks out before the crust sets. Everything else in this recipe is forgiving; those two steps are not.
If something goes sideways
- Breading falls off the mushroom in the oil: The mushroom surface was probably wet. Pat it completely dry after scraping the gills, and make sure it’s fully cold before you coat it. Wet or warm mushrooms won’t hold the egg wash properly.
- Cheese leaks out during frying: The freeze time wasn’t long enough, or the mushroom cap edges weren’t pressed together tightly. Next time, pinch the edges firmly and give it a full 20–25 minutes in the freezer — not just the fridge.
- Beef patty puffs up in the center while cooking: Make a small shallow dimple in the center of each raw patty with your thumb before it hits the pan. The patty will cook flat instead of doming up.
- ShackSauce tastes flat: Add a small splash more pickle brine and let it sit for five minutes. The flavors need a moment to come together — tasting it immediately after mixing will always undersell it.
- Potato bun gets soggy before you finish building the burger: Toast the cut sides in the same pan you used for the beef — residual fat, 30 seconds, medium heat. Then spread the ShackSauce on the toasted side right before assembly, not ahead of time.
Leftovers and meal prep
The beef patty reheats fine — wrap it loosely and microwave on medium power for 45–60 seconds, or warm it in a covered skillet over low heat. The fried mushroom is trickier: refrigerate it in an airtight container and it’ll keep for up to two days, but reheat it in an oven or air fryer at 375°F for 8–10 minutes to bring back some crunch. A microwave will make the breading soft and the cheese greasy. Don’t freeze a fully assembled burger or a pre-fried stuffed mushroom — the breading turns to mush. If you want to get ahead, you can stuff and freeze the raw mushrooms (before breading) for up to one month; bread and fry them straight from frozen, adding about two extra minutes to the fry time.
Shake Shack-Inspired Shack Stack Burger
Ingredients
For the Cheese-Stuffed Portobello Patty:
- 4 large portobello mushroom caps stems removed and gills scraped clean
- 8 slices Muenster cheese or substitute with Monterey Jack
- 1 cup all-purpose flour for dredging
- 2 large eggs beaten
- 1 cup panko breadcrumbs for coating
- 1 quart vegetable oil for deep-frying
For the Beef Patties:
- 1 ½ pounds ground beef (80/20) chilled
- ½ teaspoon kosher salt plus more to taste
- 4 slices American cheese traditionally used for melting
For the Assembly:
- 4 pieces potato burger buns lightly toasted
- 4 leaves green leaf lettuce washed and dried
- 4 slices ripe tomato 1/4-inch thick slices
- 4 tablespoons ShackSauce see chef’s tips or use your favorite burger sauce
Instructions
- Prepare the Cheese-Stuffed Mushrooms: Place 2 slices of cheese between two portobello caps like a sandwich. Press together gently. Dredge in flour, dip into beaten egg, then coat generously in panko. Repeat for all mushrooms and chill for 10 minutes in the fridge.
- Deep-Fry the Mushrooms: In a Dutch oven or deep saucepan, heat vegetable oil to 350°F (175°C). Fry each stuffed portobello for 3–4 minutes per side until golden brown and crispy. Drain on a wire rack or paper towels.
- Form Beef Patties: Divide beef into 4 loose balls and flatten into 4"-inch patties. Season both sides with kosher salt just before cooking.
- Cook the Patties: Heat a cast-iron skillet or griddle over medium-high. Cook patties for 2 minutes, smash with spatula, and cook another 2 minutes. Flip, add American cheese, cover to melt, and cook 1 more minute.
- Toast Buns: Lightly butter and toast the potato buns on a skillet or griddle until golden brown (about 1 minute).
- Assemble the Shack Stack: On the bottom bun, spread 1 tablespoon of ShackSauce, place a leaf of lettuce, followed by a tomato slice, then the cheeseburger patty. Stack the fried cheese-stuffed mushroom on top and finish with the top bun.
Notes
- ShackSauce Tip: Mix 1/2 cup mayo, 1 tbsp ketchup, 1 tbsp Dijon, 1/2 tsp garlic powder, and 1/2 tsp pickle juice.
- For a vegetarian version, skip the beef patty and double the stuffed mushrooms.
- To speed up prep, pre-bread mushrooms a day in advance and refrigerate covered.
- Add pickled jalapeños or caramelized onions for a flavor twist.
Nutrition
Your questions, answered
Can I use a different mushroom if I can’t find portobello caps?
Large cremini mushrooms are the closest substitute, but they’re smaller, so you’ll get less cheese per bite. Avoid flat mushrooms without a natural cup shape — they won’t hold the filling.
What oil temperature should I use for frying the mushroom?
350°F (175°C) is the target. Too low and the breading absorbs oil and goes greasy before it crisps; too high and the outside browns before the cheese inside has time to melt fully.
How do I know when the beef patty is done?
Ground beef needs to reach 160°F (71°C) internal temperature — use an instant-read thermometer if you’re unsure. At that temp the juices run clear and there’s no pink in the center.
Can I make the ShackSauce ahead of time?
Yes, and it actually tastes better after sitting in the fridge for a few hours. Store it in a sealed jar for up to five days.
I don’t have Martin’s potato rolls — what bun should I use?
Any soft, slightly sweet burger bun works. Brioche buns are the easiest swap and are widely available. Avoid dense or crusty rolls — they fight the soft layers of this burger rather than complementing them.
Can I make this without a deep fryer?
A deep, heavy skillet with about two inches of oil works perfectly well. A cast iron pan holds heat steadily, which helps keep the oil temperature consistent while the mushroom cooks.
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