Caramelize the onions: In a large cast-iron skillet over medium heat, melt butter with a drizzle of oil. Add onions and sauté for 5 minutes or until they start to sweat and shrink a little. Lower the heat to medium-low, add the thyme and sugar and continue to cook for 35-45 minutes, stirring every 5 minutes until the onions are caramelized. If the onions are caramelizing too fast, turn down the heat.

Flavor the onions: Add the vinegar to deglaze the pan, and season with salt. Scrape to pick up any stuck-on bits from pan. Remove from heat and allow the onions to cool to room temperature. Refrigerate the onions or complete the dip then refrigerate.

Make the dip: Combine the cream cheese, sour cream, onion powder, garlic powder, Worcestershire, and 1 tablespoon of ranch seasoning. with a spatula, or with a hand mixer on low speed. Once smooth, stir in the caramelized onions and chopped parsley. Taste and adjust with additional ranch seasoning, salt, and pepper to taste.

Rest is best. Let the dip rest for at least an hour before serving so the flavors have a chance to blend. Making it 24 hours in advance is even better! Dip is best served when removed from the refrigerator 30 minutes before serving.