Slice all 4 onions into thin-ish rounds.
Heat olive oil + salted butter in a large pan on medium heat.
Add the onions, salt and pepper and saute for 10 minutes.
Reduce the heat to medium-low and cook, stirring occasionally for 35 minutes until the onions are browned and carmelized.
Allow the onions to cool for a minute and slice into smaller pieces.
Place the cream cheese, sour cream and mayonnaise into a bowl and mix with chopped onions, taste for seasoning.
Serve at room temperature.
