Copycat Shake Shack ShackBurger Shroom Burger

Prep time: 20 min Cook time: 15 min Servings: 4

Shake Shack’s Shroom Burger is proof that a vegetarian burger doesn’t have to apologize for existing. There’s no bean patty pretending to be beef. Instead, it’s a whole portobello mushroom cap stuffed with a blend of melted Muenster and cheddar cheese, breaded and fried until the outside shatters when you bite through it, and the inside oozes with a molten cheese core. Served on a squishy potato bun with lettuce, tomato, and Shake Shack’s signature ShackSauce, it’s one of the best vegetarian fast-food items in the country.

The Shroom Burger is also one of the more expensive items on Shake Shack’s menu, often running $8.50 to $9.50 for a single burger. At home, portobello caps cost about $1 each, and the cheese, breading, and bun add another $2. For a total cost of roughly $3 per burger, you get the same experience for a third of the price.

This recipe walks through every step, including the brief freeze that prevents the cheese from escaping during frying. Don’t skip that step — it’s the difference between a cheese-stuffed mushroom and a mushroom sitting in a puddle of melted cheese.

Why Make It at Home?

A single Shroom Burger at Shake Shack costs $8.50 to $9.50 depending on the location. Making four at home costs approximately $12 total, or $3 per burger. That’s a savings of about 60%. If you feed a family of four at Shake Shack, the Shroom Burgers alone run $35 to $38 before drinks and fries. At home, the same four burgers cost $12, and you can make fries and shakes alongside for another $5 to $6.

You also get to fry them to your preferred level of crispness. The restaurant version can vary by location, but your home version is always fried exactly the way you like it.

What Makes Shake Shack’s Shroom Burger So Good

The cheese blend is the first critical element. Muenster melts into a smooth, stretchy, almost fondue-like consistency. Cheddar adds sharpness and depth. Together, they create a filling that’s gooey and rich without being bland. The cheese does the heavy lifting for flavor inside the burger, so the combination matters.

The portobello mushroom provides an earthy, meaty base that stands up to the cheese and breading. The cap’s natural concave shape makes it a perfect vessel for the filling — it’s like nature designed it to be stuffed. Removing the gills is important because they hold moisture and can make the mushroom soggy during cooking. Once the gills are gone, you have a clean, firm cup that crisps up nicely in the fryer.

The breading is what makes this a burger rather than a stuffed mushroom appetizer. The panko coating creates a crunchy, golden shell that provides textural contrast to the soft mushroom and molten cheese inside. Panko breadcrumbs are coarser and lighter than standard breadcrumbs, which means they fry up crispier and don’t absorb as much oil. The three-step dredge (flour, egg, panko) builds layers that adhere firmly to the mushroom surface and don’t flake off during cooking.

ShackSauce ties it together. The sauce is a combination of mayonnaise, ketchup, yellow mustard, finely diced pickles, and a pinch of cayenne. It’s tangy and slightly spicy, which cuts through the richness of the fried cheese and mushroom. Without it, the burger risks being one-dimensionally rich.

Tips & Variations

• Freeze before breading. Fifteen minutes in the freezer firms the cheese enough to survive the breading process and the first minute of frying. Skip this step and the cheese melts out before the coating sets.

• Press the panko on firmly. Don’t just dip — press the breadcrumbs into the egg-coated mushroom with your hands. A thick, even layer of panko is what gives you the signature crunch.

• Monitor your oil temperature. At 350 degrees, the breading crisps at the same rate the cheese melts. Too hot and the outside burns before the cheese is fully melted. Too cool and the breading absorbs oil and turns greasy.

• Make ShackSauce from scratch. Combine 1/2 cup mayo, 1 tablespoon ketchup, 1 tablespoon yellow mustard, 2 tablespoons diced dill pickles, and 1/4 teaspoon cayenne. Mix and refrigerate for 30 minutes before using.

• Double-bread for extra crunch. After the first panko coat, dip back in egg and coat with panko a second time. This creates an even thicker, crunchier shell.

Storage & Reheating

Fried shroom burgers are best eaten within 15 minutes of cooking. The breading softens and the cheese re-solidifies as it cools, losing the contrast that makes the burger work. If you have leftovers, store them unassembled (no bun, lettuce, or sauce) in an airtight container in the refrigerator for up to 2 days.

Reheat in a 400-degree oven for 8 to 10 minutes on a wire rack. This re-melts the cheese and re-crisps the breading. You can also use an air fryer at 375 degrees for 5 to 6 minutes. Avoid the microwave entirely — it makes the panko coating go limp and the mushroom releases moisture that soaks into the breading. Assemble on a freshly toasted bun with cold toppings and sauce after reheating.