Double Cheeseburgers with Caramelized Onions Recipe - Details, Calories, Nutrition Information | Rec

Ingredients

• 2 tbsp unsalted butter
• 1 sweet onion, thinly sliced
• salt
• freshly ground black pepper
• 1/2 cup mayonnaise
• 1 tbsp fresh lemon juice
• 1 clove (small) garlic, mashed
• 1 1/2 tsp smoked paprika
• 1/2 tsp cayenne pepper
• 1/4 cup extra-virgin olive oil
• 1 tbsp cornichons, chopped
• 1 tbsp flat-leaf parsley, chopped
• 6 oz gruyere cheese, shredded
• 6 oz sharp cheddar cheese, shredded
• 3 lb ground beef chuck , shaped into twelve 1/2-inch-thick patties
• toasted brioche buns , for serving
• bread -and- butter pickles , for serving
• shredded lettuce , for serving