Ingredients

1. 3 tablespoons olive oil
2. 4 small to medium size onions, chopped
3. 1 ½ shallots, finely chopped
4. 3 sprigs fresh thyme, plus more for garnish
5. 2 tablespoons balsamic vinegar
6. 2 tablespoons Worcestershire sauce
7. Coarse salt and freshly ground black pepper
8. 1 (8-ounce) package cream cheese, room temperature
9. ½ cup Crème Fraiche
10. 2 tablespoons mayonnaise
11. ¾ teaspoon celery seed

1. Heat olive oil in a large sauce pan over medium heat.
2. Cook until onions are completely caramelized, taking care not to let them scorch, about 45 minutes.
3. Add vinegar and Worcestershire sauce and cook until slightly thickened, about 10 minutes more. Season with salt and pepper; remove from heat and let cool to room temperature.
4. Meanwhile, use an electric mixer to beat cream cheese, crème fraiche, and mayonnaise together until fluffy. Add cooled onions and celery seeds; stir to combine. Transfer to refrigerator to chill at least 2 hours.