What do you get when you combine rye bread, a mushroom-packed veggie burger, slightly caramelized onions and swiss cheese? A fantastic meatless version of the classic patty melt sandwich that is hard not to love. Cooked up grilled cheese-style, this meal keeps finding its way to our dinner table time and time again.
While the recipe does take a bit of time, both the burgers and the onions can be made in advance and stored in separate containers in the refrigerator. When you are ready to eat, the sandwiches just need to be assembled and grilled up in a skillet, making for a quick and easy meal.
Traditionally, patty melts are made with beef hamburger patties, along with rye bread, swiss cheese and caramelized onions. In our meatless version, plenty of baby bella mushrooms are used in the vegetarian patty, to help give the burgers a sort of meaty texture. Both fresh and dry herbs, tomato paste and worcestershire (make sure to look for a vegetarian variety) are also added to the burger base, to really increase the savory flavors. Cannellini beans, an egg, bread crumbs and flour are added to the mix, which help give the burger a nice and sturdy texture.
The mixture for the patties will be on the wet side, but you should be able to pat it into large burgers on the baking sheet. If it seems overly wet, you can add in extra flour, about 1 tablespoon at a time, until it reaches a point where you can form it into the patties. However you want to avoid adding too much extra flour, as this could dry them out after baking in the oven.
For the burgers:
- 1 tablespoon olive oil
- 16 ounces baby bella mushrooms stemmed and chopped
- 1 15-ounce can cannellini beans, drained and rinsed
- ¼ cup minced onion
- 2 cloves garlic minced
- 2 tablespoons minced fresh parsley
- ½ cup panko bread crumbs
- ¼ cup all-purpose flour
- ½ teaspoon dried oregano
- ¼ teaspoon salt
- ¼ teaspoon Black Pepper
- 1 large egg
- 1 teaspoon tomato paste
- 1 teaspoon vegetarian worcestershire sauce
- 8 slices rye bread
- 4 slices swiss cheese
- Softened butter
To make the burgers:
- Preheat the oven to 350ºF. Line a large baking sheet with parchment paper and set aside.
- Add the olive oil to a large skillet set over medium heat. When hot, add in the mushrooms and cook until tender and the liquid released has been cooked off, about 8 to 10 minutes. Remove from the heat and set aside to cool slightly.
- Meanwhile, add the beans to the bowl of a food processor. Pulse until about half of the beans are pureed, but the rest still have some texture. Add to a large bowl, along with the onion, garlic, parsley, bread crumbs, flour, oregano, salt and pepper. Add the mushrooms to the bowl of the food processor (save the skillet for later) and pulse until finely chopped. Add to the large bowl and mix to combine. Taste and season with additional salt and pepper if needed.
- In a small bowl, beat together the egg, tomato paste and worcestershire with a fork. Stir into the bean / mushroom mixture. Pat the mixture into four large patties (about 4 inches in diameter) on the prepared baking sheet.
- Bake for about 25 to 30 minutes, until firm and lightly browned.
To make the onions:
- Meanwhile, carefully wipe out the large skillet you used for the mushrooms. Add the olive oil and set it back over medium heat. When hot, add in the onion, salt and pepper. Cook, stirring often, until lightly golden and slightly caramelized, about 15 minutes, turning down the heat to medium-low / low as needed so that they do not burn.
To make the sandwiches:
- Heat a large griddle or a large nonstick skillet over medium heat.
- Set four slices of the bread on a work surface. Top each with a burger patty, a slice of cheese, some of the onions and finally another piece of bread. Spread some of the butter on the top and bottom of each sandwich.
- Transfer the assembled sandwiches to the heated griddle and cook, carefully flipping once halfway through, until golden brown on each side and the cheese is melted.