Caramelized Onion Dip

Name: Caramelized Onion Dip
Prep time: 15 min
Cook time: 1 h
Total time: 1 h 30 min
Yield: 10
Ingredients: Ingredients; 3 large yellow onions, thinly sliced; 3 tablespoons butter; 1 tablespoon olive oil; 1/2 teaspoon salt; 1/4 teaspoon black pepper; 2 tablespoons brown sugar; 2 tablespoons balsamic vinegar; 8 oz cream cheese, softened; 1/2 cup sour cream; 1/2 cup mayonnaise; 1 packet onion soup mix; 2 tablespoons fresh chives, chopped; 1 tablespoon fresh thyme leaves; 1/2 cup gruyere cheese, grated (optional)