Smash Burger Topped with Turkey Baconnaise Sauce and Caramelized Onions - cookrisp

Ingredients

• 1 lb ground beef (80/20)
• 4 hamburger buns
• 2 large yellow onions, sliced
• 2 Tbsp butter
• 1 Tbsp olive oil
• ½ tsp salt
• ¼ tsp black pepper
• ½ cup mayonnaise
• 2 Tbsp chopped cooked turkey bacon
• 1 tsp Dijon mustard
• 1 tsp maple syrup
• Pinch of black pepper
• Sliced cheddar cheese
• Lettuce leaves