French Onion Burgers

French onion burger with caramelized cheese, melted cheese and lettuce sitting on a wooden board.

5 from 1 vote

Try this French onion burger for a fun twist on the classic soup we all know and love! Incredibly juicy and flavorful burger patties spiced with fresh garlic, thyme, and Worcestershire sauce, topped with mouthwatering caramelized onions and a mix of melted Gruyère and provolone cheese.

Prep Time15

Cook Time45

Total Time1

Course: Dinner

Cuisine: American

Servings: burgers

Calories: 537kcal

Author: Christina

Ingredients

4 Tablespoons unsalted butter
2 sweet onions thinly sliced
1 ½ teaspoons salt divided
2 teaspoons minced garlic divided
1 teaspoon fresh thyme minced
2 Tablespoons all-purpose flour
½ cup low-sodium beef broth
2 pounds 85-87% lean ground beef
2 teaspoons Worcestershire sauce divided
1 teaspoon black pepper divided
8-10 slices Gruyère or provolone cheese or both!
for serving: hamburger buns additional toppings like lettuce, tomatoes, pickles, etc.

Instructions

In a large skillet over medium heat, add the butter and onions. Sauté for 5-7 minutes until the onions begin to soften. Add ½ teaspoon salt and cook for 30 minutes, stirring every few minutes, until the onions are very soft and golden brown. If the onions start to stick to the pan, reduce the heat to medium-low. Stir in ½ teaspoon thyme and 1 teaspoon garlic, and let it cook for 1 minute. Stir in the flour and cook for 2-3 minutes to remove the flour taste. Then, whisk in the beef broth until the onion mixture thickens. Remove from the heat and set aside.
Line a large baking sheet or plate with parchment paper. Set aside. Combine the ground beef, Worcestershire sauce, black pepper, and remaining salt, garlic, and thyme. Mix together until combined– the best way to do this is with your hands or with a wooden spoon or rubber spatula.
Divide the ground beef mixture into 6 sections, roughly a heaping ½ cup for each (for 8 burgers, use a heaping ¼ cup for each.) Form each patty freeform or use a burger mold– each should be around 4-5 inches wide (about 1 inch larger than the bun as the burgers will shrink as they cook.) Place each formed patty onto the prepared baking sheet while you form the remaining. The total cook time is 9-10 minutes. Let the patties rest for 5 minutes while the grill preheats in the next step. This can be done while the onions are cooking.
Preheat the grill to high (500ºF-550ºF.) Place the burgers on the heated grill and cook for 5 minutes with the lid closed. Flip the burgers and cook for an additional 4-5 minutes or until a meat thermometer reads 150ºF. About 1 minute before the burgers finish, top with cheese slices and close the lid to allow the cheese to melt. Keep an eye on the burgers as the time can vary slightly based on the thickness of the patty (thinner patties = less time.) Set the cooked burgers on a baking sheet or plate covered with aluminum foil and allow them to rest for 2-3 minutes to allow the juices to redistribute throughout the burger. The patties will not stick to a clean, well-oiled surface or grill.
Serve on a toasted hamburger bun, topped with caramelized onions and additional desired toppings such as lettuce, tomato, mayo, pickles, or whatever your favorite toppings are. Leftover burgers stay fresh in the refrigerator for up to 5 days.

Notes

Make Ahead Instructions: You can shape the burger patties up to 2 days in advance. Place parchment paper between each and store in an airtight container or bag on a flat surface. The caramelized onions can be made up to 3 days in advance. Reheat over low heat or in the microwave.
Freezing Instructions: Uncooked patties can be frozen for up to 3 months. Place parchment paper between each and store in a freezer-safe airtight container. Thaw overnight in the refrigerator and cook as directed in step 4, or you can grill from frozen for an additional 3-5 minutes. The cooked burgers can be frozen for up to 3 months, allow them to cool completely then place parchment paper between each and store in a freezer-safe container or bag. Thaw overnight in the refrigerator and heat up to your liking.
Ground Beef: The leaner the ground beef the more dry the burger will be. I recommend 87% lean for the best results.
Onions: Make sure the onions are evenly sliced to allow for even cooking. I recommend thinly slicing as it speeds up the caramelization process and time.
Make 8 Burgers: Instead of 6 burgers, you can make 8 using a heaping ¼ cup of the ground beef mixture. The cook time will be slightly less since it's a thinner patty.
Cook Times: You can use the following temperatures depending on preference (1) medium-rare 130ºF-135°F, (2) medium 140ºF-145°F, (3) medium-well 150ºF-155°F (4) well done 160°F+.

Nutrition