• 3 tablespoons unsalted butter
  • 2 pounds yellow onions, halved and thinly sliced
  • 4 teaspoons minced garlic
  • leaves from 2 sprigs thyme
  • 1 sprig fresh rosemary
  • 3 cups Progresso chicken or vegetable broth, divided
  • 3 pounds boneless, skinless chicken thighs
  • 1 tablespoon balsamic vinegar
  • 2 tablespoons Dijon mustard
  • 1 cup shredded Gruyere cheese


  1. In a large skillet over medium heat, melt butter. Add onions and salt and pepper to taste; stir to coat. Reduce heat to medium-low; cook onions, stirring occasionally until caramelized, about 40 minutes.
  2. When onions are just about caramelized, add minced garlic, thyme leaves and rosemary sprig; increase heat to high. Cook onions another 5 minutes, stirring frequently, until fully caramelized and darkly browned in some spots.
  3. Add 1 cup broth and stir vigorously, scraping bits from bottom of skillet. Reduce heat and simmer 5 minutes, until liquid is reduced slightly. Remove from heat; pour onions and liquid in the bottom of a Dutch oven or other oven-safe dish and set aside.
  4. Return skillet to stovetop and increase heat to medium-high; heat oven to 325 degrees F, as well. Pat chicken thighs dry and season with salt and pepper; add to skillet. Cook until golden brown on both sides, about 5-10 minutes. Remove chicken from skillet and place over onions in dish.
  5. Add 1 cup broth to the hot pan; stir vigorously, scraping up brown bits from the bottom of the pan. Add balsamic vinegar and Dijon mustard and stir to combine. Simmer liquid, stirring frequently, until liquid is reduced by half. Pour liquid over chicken and onions in dish. Add remaining broth and cover with a lid.
  6. Bake until chicken is baked through, about 30 minutes. Remove dish from oven; heat broiler. Sprinkle top of chicken with shredded Gruyere cheese. Return to oven until cheese is melted and browned on top, about 4 minutes. Remove from oven; spoon into bowls and serve.