Peel and thinly slice the yellow onions. Heat butter in a skillet over medium-high heat. Add onions and stir occasionally.
Once they begin to brown, lower the heat to medium-low and cook for 20-25 minutes, stirring occasionally, until golden and caramelized.
In a food processor, combine cream cheese, sour cream, mayonnaise, salt, and pepper.
Process until the mixture is smooth and creamy. Let the onions cool for 5 minutes, then add them to the food processor with the creamy mixture.
Pulse a few times to combine, leaving some small onion chunks for texture.
Transfer the dip to a bowl, garnish with sliced chives, and serve with chips, crackers, or fresh veggies.
Notes
Low and Slow: Take your time with caramelizing the onions to develop their sweetness and rich flavor.Room Temperature Ingredients: Let the cream cheese soften before blending for a smoother consistency.Mix to Taste: Pulse the onions into the dip lightly for a chunkier texture or blend more for a smoother dip.Make Ahead: Prepare this dip a day in advance to let the flavors meld together even more.