Peel onion, cut it in half and then slice thinly (see Notes below).
Melt butter and oil in skillet, add onion and season with salt and pepper.
Add enough tap water to just cover the onions.
Cook over slow/medium heat, stirring occasionally, for about 10-15 minutes, until the liquid evaporates.
Start stirring the onion constantly for a few minutes, until brown and caramelized.
Allow them to cool down to room temperature.
In a bowl mix cream cheese, sour cream, mayonnaise, and cooled onions, saving a tablespoon for garnish.
Add cayenne, 1 tablespoon milk or cream, and mix well. Make sure the consistency is the right one so the potato chips don't break when scooping it. Add a teaspoon or more liquid if necessary.
Check for seasonings and adjust as necessary.
Mix in chives, saving a teaspoon for garnish.
Serve at room temperature topped with some caramelized onions and chives.
Eat with potato chips.
Keep leftovers refrigerated.