• 1 tablespoon unsalted butter
• 1 large Vidalia onion, thinly sliced
• 1 package (20.8 ounces) ground turkey
• ½ cup part-skim ricotta cheese
• 1¾ teaspoons Worcestershire sauce
• 1¾ teaspoons Dijon mustard
• ¼ teaspoon salt
• ¼ teaspoon black pepper
• 1 tablespoon vegetable oil
• ¼ cup crumbled blue cheese
• 2 tablespoons light mayonnaise
• 4 whole-grain white hamburger buns
• 4 romaine lettuce leaves

1. Melt butter in a large skillet over medium-high heat. Add onion; cook for 15 minutes or until well browned; set aside.
2. In a large bowl, combine turkey, ricotta, Worcestershire sauce, mustard, salt and pepper. Stir until well combined. Form into 4 equal-size patties and flatten.
3. Heat oil in a large nonstick skillet over medium heat. Cook burgers about 5 minutes per side, then partially cover, reduce heat to medium and cook another 5 minutes or until instant-read thermometer registers 160 degrees F.
4. While burgers are cooking, stir together blue cheese and mayonnaise in a small bowl. Place burgers on buns and top each with some of the onions, 1 tablespoon blue cheese sauce and a lettuce leaf.

Makes 4 servings.