Vegetarian Mushroom Burgers

These Vegetarian Mushroom Burgers will rock your world! Take a crispy fried portobello mushroom with loads of melted cheese, add your toppings and be ready to say “YUM!”.

Last New Year’s Eve, our co-founder Catherine was at home with her family and they decided to have a cook-off. It was a great way to get the kids in the kitchen and ended up being SUCH a blast. Kenya, Catherine’s vegetarian son, decided he wanted to recreate his favorite burger, the Shroom Burger, from Shake Shack, and it turned out amazing! 

After their New Year’s Even cook-off, Catherine knew she had to test these out again. Here at One Potato, we love re-thinking burgers and coming up with something more unique than your traditional beef burger.

Why do we love this recipe? First off, the crispy-fried portobello mushroom gives a satisfying crunch, but the absolute best part is the explosion of cheese you get after you take your first bite. Who doesn’t love cheese, right? Vegetarian burgers can be just as messy and delicious as their meat counterparts. Of course, don’t forget the rest of the toppings! Lettuce, tomato, and some avocado slices.

Both vegetarians and meat-eaters alike will love this Shroom Burger. And don’t forget the Air Fryer French Fries! You can’t go wrong with a burger and fries combination. 

Vegetarian Mushroom Burgers

Prep Time 30 mins
Cook Time 45 mins
Servings 4 servings


Vegetarian Mushroom Burgers

  • 4 large portobello mushroom caps, stems sliced off
  • Olive, vegetable, avocado, or canola oil
  • 1 tsp kosher salt
  • 1 1/2 cups plus 1 tsp all purpose flour, divided
  • 4 large eggs
  • 2 cups panko bread crumbs
  • 1 1/2 cups mozzerella cheese
  • 1/2 cup gruyere or cheddar cheese
  • 1/4 tsp onion powder
  • 1/4 tsp garlic powder

Faux Shake Shack Sauce

  • 1/2 cup mayonnaise (or vegan mayonnaise)
  • 1 tbsp dijon mustard
  • 1 tsp ketchup
  • 1 tsp dill pickle juice (from jar of pickles)
  • 1 pinch cayenne pepper (optional)


  • 4 hamburger buns
  • 1 ripe tomato, sliced into 4 1/4 inch slices
  • 1/2 ripe avocado, peeled and cut into 1/4 inch slices
  • 4 pieces romaine or other crisp lettuce


Vegetarian Mushroom Burgers

  • Preheat oven to 375 degrees. Place the mushrooms on a parchment lined baking sheet, rub with oil and sprinkle with salt on both sides. Place mushrooms gill side down and roast for 30-35 minutes or until slightly golden. Remove from oven and allow to cool.
  • Slice the mushroom caps horizontally being careful to make sure to cut directly through so both sides are even.
  • Create a breading station. Place the flour in a deep bowl or pie plate. Whisk 3 of the eggs in a similar sized bowl and the panko in a third bowl.
  • For the filling, place the cheeses, onion and garlic powder and one egg in a medium sized bowl and stir to throughly combine. Form the mixture into 4 even sized disks just smaller than the mushrooms. Place a disk of the cheese in between each mushrooms to create a sandwich and press to secure.
  • Dredge each stuffed mushroom in the flour, then the whisked egg and finally coating with the panko, pressing to adhere.*
  • Heat a large sauté or cast-iron pan with 1 inch of oil over medium high heat (if using a candy thermometer it should read 350 degrees). Fry the burgers on each side for 3-4 minutes or until golden and crisp. Transfer the burgers to a paper towel lined plate to remove excess oil.


  • Place the sauce ingredients in a bowl and stir to combine.

Burger Assembly

  • Place a shroom burger on the bottom of a bun, top with avocado, tomato, lettuce and sauce if desired and top with second bun.


  • Note: mushroom burgers can be refrigerated overnight at this point.