Melt the Butter - Set a large pot or dutch oven over medium-high heat. Melt the butter then add olive oil, brown sugar, ½ teaspoon salt, pepper. Stir to combine.
Caramelize the Onions - Immediately add in the onions and stir to coat. Saute while frequently stirring until they begin to soften and lightly brown, about 5 minutes. Reduce the heat to medium. Continue cooking while frequently stirring until evenly browned, 10 minutes.
Deglaze the Pan - Add 2 tablespoons of water, stir and scrape to deglaze the pan—Cook for 5 minutes. Add the remaining water and deglaze again, cook until brown, 5 minutes.
Saute the Garlic - Add the garlic and frequently stir until fragrant and the onions turn deep brown, about 4 to 5 minutes.
Let it Cool - Add the caramelized onions to a medium bowl, then transfer to a refrigerator until cool, about 10 minutes.
Mix the Dip - To the medium bowl, add the sour cream, mayonnaise, Worcestershire sauce, ¼ teaspoon salt, onion powder, and black pepper. Stir together until smooth. Season with more salt and pepper to taste.
Serve - Transfer dip to a serving bowl. Garnish with chopped chives. Serve with chips or vegetables.
Recipe Yield: About 3 cups
Serving Size: ¼ cup
Storing: Store in an airtight container for up to 5 days.
Worchestershire Substitute: 1 teaspoon soy sauce and ½ teaspoon apple cider vinegar or rice vinegar.