Jalapeño-Onion Smash Burgers with Caramelized Onions and Cheese - Yummy Gusto

Ingredients

• 45 ml mayonnaise
• 22 ml ketchup
• 5 ml Worcestershire sauce
• 2 g freshly ground black pepper
• 1 g garlic powder
• 1 g kosher salt
• 680 g 80% lean ground beef
• 5 ml canola oil
• 1 large yellow onion, thinly sliced (approximately 240 g)
• 1 large jalapeño, thinly sliced (approximately 60 g)
• 7 g kosher salt, divided
• 3 g freshly ground black pepper, divided
• 4 slices American cheese
• 4 hamburger buns, split and toasted