Brussels Sprout Melts

published Nov 7, 2022
Brussels Sprout Melts Recipe

If you think the magic of the patty melt feels out of reach for vegetarians, this gooey Brussels sprouts sandwich will make you reconsider.

Serves4

Makes4 sandwiches

Prep20 minutes

Cook30 minutes to 45 minutes

Jump to Recipe
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brussels sporuts melts stacked
Credit: Photo: Andrew Bui; Food Styling: Jessie YuChen

Patty melts have been a staple of American cuisine for close to a century — and for good reason. Toasted rye bread with sweet caramelized onions, melted Swiss cheese, and a buttery beef patty is a winning combination. Restaurateur Tiny Taylor is said to have invented the sandwich sometime around 1950 in Los Angeles, and to this day the sandwich can be seen on almost any diner menu.

If you avoid eating meat, the magic of the patty melt might seem out of reach — but fret not! There are several delicious ways to experience the deliciousness of patty melts that don’t include beef. If you replace the meat with something that provides a hearty base (like mushrooms or tofu) you can still experience a patty melt’s beloved combination of textures and flavors, all without the meat.

This version is loaded with Brussels sprouts that get cooked alongside caramelized onions to create a sweet-and-savory filling that is packed with flavor. It’s hearty, rich, and (in my humble opinion) better than the original. So whether you don’t eat meat or simply want to eat a really delicious sandwich that just happens to be vegetarian, these patty melts are for you.

Credit: Photo: Andrew Bui; Food Styling: Jessie YuChen

Tips for Making Perfect Brussels Sprout Melts

Before you start cooking these Brussels sprout melts, keep these tips in mind.

  1. Take your time caramelizing the onions. It will take at least 20 minutes for the onions to caramelize, so don’t rush it. The slow process caramelizes their natural sugars and makes them the perfect bittersweet counterpart to the savory Brussels sprouts and cheese. 
  2. Pick out a nice rye bread. If you’re nervous that the rye bread might overpower the flavor of the sandwich, don’t worry — the nuttiness of the rye adds a wonderful robustness to the sandwich that helps bring it to life. You can feel free to use a dark rye, light rye, seeded rye, or marbled rye.
  3. Cook the patty melts over medium-low heat. The gentle heat will slowly warm the sandwiches so by the time the bread is toasted the cheese will be completely melted. Don’t be tempted to increase the temperature to speed things up; this will only result in sandwiches with unmelted centers.

Brussels Sprout Melts Recipe

If you think the magic of the patty melt feels out of reach for vegetarians, this gooey Brussels sprouts sandwich will make you reconsider.

Prep time 20 minutes

Cook time 30 minutes to 45 minutes

Makes 4 sandwiches

Serves 4

Nutritional Info

Ingredients

  • 8 tablespoons (1 stick)

    unsalted butter, divided

  • 2

    large yellow onions (about 11 ounces each)

  • 8 ounces

    Brussels sprouts

  • 8 ounces

    Swiss cheese, shredded (about 2 cups)

  • 1 teaspoon

    Worcestershire sauce or balsamic vinegar

  • 1/2 teaspoon

    kosher salt, plus more as needed

  • 1/2 teaspoon

    freshly ground black pepper

  • 8

    (1/2 to 3/4-inch thick) slices rye bread

  • 4 tablespoons

    Dijon mustard, divided

Instructions

  1. Place 4 tablespoons of the unsalted butter on the counter and let sit at room temperature to soften. Meanwhile, make the filling.

  2. Halve and thinly slice 2 large yellow onions until you have about 5 cups. Melt the remaining 4 tablespoons unsalted butter in a large nonstick or cast-iron skillet over medium heat. Add the onions and cook, stirring occasionally, until jammy and dark brown (similar in color to mahogany), 20 to 25 minutes. This process will take time; don’t rush it. If the bottom of the pan starts to burn before the onions caramelize, add 1 tablespoon of water to the pan and scrape the bottom. Repeat this as many times as necessary to prevent burning. Meanwhile, prepare the Brussels sprouts and cheese.

  3. Trim the root end from 8 ounces Brussels sprouts and thinly slice into ribbony rounds (about 2 1/2 cups). If needed, grate 8 ounces Swiss cheese on the large holes of a box grater (about 2 cups).

  4. When the onions are ready, add the Brussels sprouts, 1 teaspoon Worcestershire sauce or balsamic vinegar, 1/2 teaspoon kosher salt, and 1/2 teaspoon black pepper to the pan. Cook, stirring often, until the Brussels sprouts are tender, lightly browned in spots, and wilt, 5 to 7 minutes. (If the bottom of the pan starts to burn, continue adding water 1 tablespoon at a time as needed.)

  5. Transfer the mixture to a large bowl and let cool until warm but no longer hot, about 10 minutes. Meanwhile, wash and dry the pan used to cook the onions.

  6. Add the cheese to the onion mixture and toss to combine. Taste and season with more kosher salt as needed.

  7. Heat the same pan over medium-low heat. Meanwhile, assemble the sandwiches: Spread one side of 8 slices of rye bread with the softened butter (about 1/2 tablespoon per slice). Flip 4 of the slices over; spread 1 tablespoon Dijon mustard on each of these slices. Divide the Brussels sprouts mixture onto the mustard slices and arrange into an even layer all the way to the edge. Close the sandwiches with the remaining bread slices buttered-side up.

  8. Add 2 of the sandwiches to the pan and cook until the bread is golden brown and the cheese is completely melted, 4 to 5 minutes per side. Transfer to a clean cutting board and repeat cooking the remaining 2 sandwiches. Cut each sandwich in half.

Recipe Notes

Make ahead: The caramelized onion and Brussels sprouts mixture can be cooked and refrigerated in an airtight container up to 3 days in advance. Mix in the shredded cheese right before assembling the sandwiches.