Caramelized Onion and Parmesan Burgers Recipe

Getty Images / JoeGough 

Prep: 25 mins
Cook: 30 mins
Refrigeration: 60 mins
Total: 115 mins
Servings: 8 servings
Yield: 8 burgers
Nutrition Facts (per serving)
352 Calories
12g Fat
34g Carbs
26g Protein
Show Full Nutrition Label Hide Full Nutrition Label
Nutrition Facts
Servings: 8
Amount per serving
Calories 352
% Daily Value*
Total Fat 12g 16%
Saturated Fat 4g 21%
Cholesterol 100mg 33%
Sodium 404mg 18%
Total Carbohydrate 34g 12%
Dietary Fiber 3g 10%
Total Sugars 6g
Protein 26g
Vitamin C 7mg 33%
Calcium 148mg 11%
Iron 5mg 28%
Potassium 590mg 13%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)

The first time I made these for my family, I didn’t mention the fact that they were half mushroom, half beef (otherwise known as The Blend – I feel like it needs a soundtrack to go with this dramatic name); I just said they were burgers. No questions were asked, and the burgers were completely devoured.

According to The Mushroom Council, many chefs are finding that you can blend chopped mushrooms with ground meat to create better tasting, more nutritious burgers – good for you, but also good for the environment, as even non-vegetarians know that reducing overall consumption of meat is a great thing for the earth. 

Mushrooms, like beef, are a great source of umami, which is also known as the fifth taste – think meaty, think deep, think “a pleasant savory taste” which is how it translates from Japanese. Mushrooms are extremely low in calories, and have no fat, so by blending them with flavorful, rich ground beef, you get the best of both worlds. You can use this technique with all kinds of meat, from beef to lamb to buffalo to sausage to turkey. You can also have a very good time exploring the wide world of mushrooms. In this recipe I used a mix of cremini and button mushroom, inexpensive and very readily available, but you should feel very free to change up flavors with other varieties like criminis, portabellas, shiitake, maitake (also known as hen of the woods), oyster, trumpet and more.

Richly caramelized onions provide another wonderful depth of flavor to this burger.  The longer you can cook the onions, the better, but keep the heat low and stir frequently so that they don’t burn.


  • 2 teaspoons olive oil, plus more for frying

  • 2 medium yellow onions, thinly sliced

  • 1 pound button mushrooms, or cremini mushrooms, or a mixture

  • 1 pound 90 percent lean ground beef

  • 2 large eggs, beaten

  • 3 tablespoons panko breadcrumbs

  • 1/4 cup finely grated Parmesan cheese

  • 1/4 cup minced fresh parsley

  • 8 hamburger buns (preferably whole wheat)

  • Lettuce, sliced tomatoes, sliced onions, ketchup, mustard, for optional toppings

Steps to Make It

  1. Gather the ingredients.

  2. Heat the olive oil in a large heavy skillet (preferably cast iron) over medium heat.  Add the onions and sauté for 15 to 20 minutes until they are golden brown and very soft….if you can sauté them for 30 to 40 minutes, even better. Let them cool to room temperature and roughly chop them.

  3. Meanwhile, wipe off any dirt from the mushrooms with a damp paper towel, trim off the bottoms of the stems, then cut the mushrooms in half.  Working in two batches, pulse them in a food processor with a metal blade until they are coarsely chopped, much like crumbly ground beef.  (You can also do this by hand with a knife and a cutting board, but do make sure the mixture is pretty finely chopped).

  4. Place the mushrooms in a large mixing bowl and add the beef, chopped onions, eggs, panko, Parmesan, and parsley.  Gently shape the mixture into 8 patties of equal side, about 3/4 –inch thick.  Place them on a cutting board or a platter and refrigerate them for an hour until firm (they can be covered and refrigerated for up to 8 hours).

  5. Lightly oil a grill pan or a cast iron skillet, or spray with nonstick cooking spray.  Heat the pan over medium high heat.

  6. Cook the patties, in batches (make sure there is space between each burger), until they are cooked through, about 8 minutes on each side – you want to get a nice sear on both sides, but make sure they don’t burn, and flip them gently, as they are a bit delicate. Adjust the heat as needed.


A Healthy Trend

This year, more than 15% of K-12 public schools will be serving “blended burgers,” or burgers made more nutritious, with less fat and sodium by blending finely chopped mushrooms with the meat.

Lunchrooms are blending burgers at a traditionally 30/70 mushroom/meat ratio to meet the USDA fat and sodium requirements for school meals.  Beyond health, mushrooms’ umami helps make the burgers more flavorful. In the past three years, more than 30 million blended burgers have been served in schools – or 500,000 pounds of mushrooms a year.