Cashew Cheese Stuffed Portobello Mushroom Burger

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The ultimate vegan Portobello mushroom burger two Portobello mushrooms stuffed with melty cashew cheese, coated in panko breadcrumbs and fried until crispy then sprinkled with rosemary salt. Layered on a toasted burger bun with a spicy cashew mayo, avocado, tomato, lettuce, and pickles if you're feeling it. Eat with thick-cut, rosemary salt sprinkled, potato or sweet potato chips, extra spicy mayo, and a cold beer for the best vegan burger meal you've ever had!

Shake Shack Double Stack Copycat: Cashew Cheese Stuffed Portobello Mushroom Burger [Vegan]


For the Cashew Cheese Filling:

  • 1 cup cashews, soaked for 6-8 hours or overnight in cold water or 2-3 hours in just boiled water
  • 1/3 cup coconut milk
  • 1/3 cup water
  • 2 tablespoons nutritional yeast
  • 1/2 teaspoon white miso
  • 1 tablespoon coconut oil
  • 1 tablespoon lemon juice
  • 2 tablespoons arrowroot starch
  • 1/2 teaspoon Dijon mustard
  • 1/4 teaspoon fine sea salt, plus more to taste
  • 1/4 teaspoon garlic powder
  • 1/8 teaspoon turmeric
  • 1/8 teaspoon paprika
  • A few cracks black pepper

For the Spicy Mayo:

  • 1 cup cashews, soaked for 6-8 hours or overnight in cold water or 2-3 hours in just boiled water
  • 5 tablespoons olive oil
  • 1/4 cup water
  • 1 teaspoon white wine vinegar
  • 1 tablespoon ketchup/tomato sauce
  • 1 teaspoon dijon mustard
  • 4 slices dill pickles
  • 1 tablespoon lemon juice
  • 1/4 teaspoon garlic powder
  • 1/4 teaspoon hot or smoked paprika
  • 1/8 teaspoon cayenne pepper
  • 1/4 teaspoon fine sea salt, plus more to taste

For the Rosemary Salt:

  • 2 tablespoons flaky sea salt
  • 1 tablespoon finely chopped rosemary
  • A few cracks of black pepper

For the Portobellos:

  • 8 large Portobello mushrooms, stems and gills removed
  • 2 cups flour
  • 2 tablespoons finely chopped rosemary
  • 1 1/2 cups almond milk
  • 3 cups panko breadcrumbs
  • Peanut oil to fry enough to fill a large pot halfway with oil, about 3 liters

For Serving:

  • 4 burger buns
  • Coconut oil to toast the buns
  • Sliced tomatoes
  • Lettuce leaves, washed and torn to burger size
  • A few thin avocado slices per burger
  • Dill pickles (optional)
  • Fries of choice


To Make the Cashew Cheese Filling:

  1. Drain and rinse the cashews, then place in a blender (preferably high-speed) with all the other ingredients and blend until completely smooth, creamy and the mix feels warm. The arrowroot should begin to "activate" making the cheese look like melty cheese fondue. Taste, adjust the seasoning if needed then scrape into a container, cover and place in the refrigerator to chill. Rinse out the blender ready to use for the mayo.

To Make the Spicy Mayo:

  1. Drain and rinse the cashews and place all the ingredients in a blender. Blend until completely smooth. Try not to over-blend or the olive oil may become bitter the mix shouldn't get too hot. Taste and adjust the seasoning if needed, scrape into a container, cover and place in the refrigerator to chill and thicken.

To Make the Rosemary Salt:

  1. In a mortar and pestle, bash together 1 tablespoon of the salt, the rosemary, and the pepper until mashed together and fragrant (alternatively you can do this in a small food processor). Stir in the remaining 1 tablespoon sea salt then scatter on a baking tray and leave to dry at room temp while you make the burgers.

To Make the Portobellos:

  1. Steam the Portobellos in a covered steaming basket, over a pot filled with about 2 inches of simmering water. Steam until completely soft, tender, and flexible (you may need to do this in two batches), about 10 minutes. When cooked, remove and place between two tea towels. Press down on the towels to help the mushrooms release their liquid. Place the mushrooms on a cooling rack and allow them to dry and cool completely.
  2. Take one Portobello, top facing down, and place 1/4 cup of the chilled cashew cheese in the middle. Place another Portobello on top. Gently press and mould the Portobellos together. You can also use a big piece of cling wrap place under the bottom Portobello, gather the ends together and twist to help mould the Portobello's together. Repeat with the other Portobellos.
  3. Mix the flour and chopped rosemary together and place on a large plate, pour the almond milk into a large bowl, and place the panko on large plate. Coat the Portobellos with the flour mix, then the almond milk, then the panko, making sure to cover the sides as well. Repeat this coating process one more time, then allow the coated Portobello burger to rest on a piece of baking paper while you repeat this process with the other 3 burgers.
  4. Heat your peanut oil to 375F use a deep fry thermometer, then gently place your burgers into the oil (fry two at a time) using a slotted spoon. Move the burgers around as they cook so that they don't sit on the bottom, and so they fry evenly.
  5. Cook until golden brown and crispy, about 4 minutes. Transfer to a tea towel lined plate, sprinkle both sides with a little rosemary salt and repeat with the remaining two burgers.

To Assemble:

  1. Cut your burger buns in half and brush both sides with a little coconut oil. Fry in a medium-high heat pan or cook under the grill until lightly toasted. Spread the top buns with about 1 tablespoon mayo. Place a few thin slices of avo on the bottom buns, then top with the fried mushroom patty, the lettuce, then the tomato (and pickles if using).
  2. Serve immediately. The best way to serve with chips tossed with rosemary salt, the leftover spicy mayo for dipping and a cold beer! The ultimate.


Inspired by and adapted from these 'Fake Shack' burgers over on Serious Eats

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