Jucy Lucy Burgers

Bahan-bahan (4 porsi)

• 1½ pounds 85% lean ground beef
• ½ teaspoon salt
• ¼ teaspoon freshly ground black pepper
• 4 slices (3-ounces) deli-style extra sharp cheddar cheese
• 1 tablespoon olive oil
• 1 large sweet onion, (thinly sliced (about 2 cups))
• ¼ teaspoon salt
• 2 tablespoons olive oil
• 3 medium garlic cloves, (thinly sliced)
• 1½ pounds Swiss chard (trimmed and center rib removed), (torn into bite-sized pieces (about 12 cups))
• ¼ teaspoon salt
• ¼ teaspoon freshly ground black pepper
• 4 potato sandwich rolls
• 4 lettuce leaves
• 4 beefsteak tomato slices