Caramelized Onion and Gruyère Burgers with Creamy Béchamel and Crispy Kale Chips

Imagine the rich, savory flavors of French onion soup transformed into a hearty burger. Sweet caramelized onions, nutty Gruyère cheese and a velvety béchamel sauce come together on a juicy beef patty, all nestled in a toasted brioche bun. It’s a match made in comfort food heaven.

And because we believe in balance, we’ve added a side of crispy kale chips. They’re light, crunchy and the perfect counterpoint to the indulgent burger. This recipe is a celebration of classic flavors in a fun, handheld form.

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Ingredients

1 unit Yellow OnionView ingredient guideLike ingredientDislike ingredient

4 ounce KaleView ingredient guideLike ingredientDislike ingredient

0.25 ounce ThymeView ingredient guideLike ingredientDislike ingredient

1 unit Beef Stock ConcentrateView ingredient guideLike ingredientDislike ingredient

0.5 cup Gruyère CheeseView ingredient guideLike ingredientDislike ingredient

1 tablespoon FlourView ingredient guideLike ingredientDislike ingredient

0.5 cup MilkView ingredient guideLike ingredientDislike ingredient

0.125 teaspoon NutmegView ingredient guideLike ingredientDislike ingredient

10 ounce Ground BeefView ingredient guideLike ingredientDislike ingredient

2 unit Brioche BunsView ingredient guideLike ingredientDislike ingredient

1 tablespoon Olive OilView ingredient guideLike ingredientDislike ingredient

1 teaspoon SugarView ingredient guideLike ingredientDislike ingredient

1 tablespoon ButterView ingredient guideLike ingredientDislike ingredient

SaltView ingredient guideLike ingredientDislike ingredient

PepperView ingredient guideLike ingredientDislike ingredient

Instructions

1. Preheat oven to 350°F. Wash and dry all produce. Halve, peel and thinly slice the onion. Remove stems and large ribs from kale, then tear leaves into bite-sized pieces. Toss kale on a baking sheet with a drizzle of olive oil and a pinch of salt and pepper. Bake until crisp, 10-12 minutes. Watch closely to prevent burning.
2. Heat a drizzle of olive oil in a large pan over medium heat. Add sliced onion and thyme sprigs. Cook, stirring occasionally, until soft and browned, 7-8 minutes. Stir in beef stock concentrate, 1 teaspoon sugar and ¼ cup water. Simmer until onion is jammy, 2-3 minutes. Remove and discard thyme sprigs. Transfer onion to a bowl and set aside. Wipe out the pan.
3. Grate Gruyère cheese on the large holes of a grater. In a small pot, melt 1 tablespoon butter over medium heat. Add flour and stir until lightly toasted, about 1 minute. Slowly whisk in ½ cup milk and simmer until thickened, 1-2 minutes. Season with a pinch of nutmeg, salt and pepper. Set aside off heat.
4. Shape ground beef into two patties slightly larger than the buns. Season generously with salt and pepper. Heat a drizzle of oil in the same pan over medium-high heat. Add patties and cook until just shy of desired doneness, 3-5 minutes per side. Sprinkle cheese on top of each patty, cover the pan and cook until cheese melts, 1-2 minutes.
5. While burgers cook, split brioche buns in half and place on a baking sheet. Toast in the oven until golden, 2-3 minutes.
6. Spread béchamel sauce onto the cut sides of the buns. Assemble burgers with patties and caramelized onions. Serve with kale chips on the side.

Recipe Tips

FAQ

Can I use a different cheese instead of Gruyère?

Yes, Swiss or provolone would work well as substitutes for Gruyère.

How do I prevent the kale chips from burning?

Watch them closely during the last few minutes of baking. They can go from perfectly crisp to burnt very quickly.

Can I make the béchamel sauce ahead of time?

Yes, you can prepare the béchamel up to a day in advance. Reheat gently on the stove, whisking in a splash of milk if needed to thin.