Patty Melt with Burger Sauce | Charlotte Fashion Plate

Ingredients

• 1 pound ground beef (80/20)
• 4 slices country-style bread
• 1 large white onion, sliced into thin half moons
• 4 tablespoons butter, divided
• 1 teaspoon salt, divided
• 1 teaspoon black pepper
• 1 teaspoon garlic powder
• 6 slices American cheese
• 6 slices Monterey Jack or Pepper Jack cheese
• 1/2 cup mayo
• 1/3 cup ketchup
• 1 tablespoon dill relish
• 1/2 teaspoon white wine vinegar
• 3 dashes Worcestershire sauce
• 1/2 teaspoon garlic powder
• 1/2 teaspoon black pepper
• Pinch of salt