1 whole sweet onion, roughly chopped
1/3 cup beef broth, + 1/4 cup
3 tablespoons sherry (or sherry cooking wine)
8 ounces cream cheese, cut into 8 pieces
1 cup shredded fresh gruyere
Add the onion, 1/3 cup beef broth, and 2 tablespoons of the sherry to a slow cooker. Cook the onions on high for 2 hours.
After 2 hours, add the cream cheese and gruyere, plus the remaining beef broth and sherry, and mix it into the onions. Let it cook on low for 1 hour, then transfer to a dish and serve.