Barefoot Contessa's Caramelized Onions

These are wonderful on top of a hamburger.

Cut the onions in half and then slice them into 1 / 8-inch thick half-rounds.

Heat the butter and oil in a large saute pan over medium heat.

Add the onions , cayenne , salt , and pepper and saute for 10 minutes.

Reduce the heat to medium-low and cook , stirring occasionally , for 20 more minutes until the onions are browned and caramelized.

yellow onions, unsalted butter, vegetable oil, ground cayenne pepper, kosher salt, fresh ground black pepper