Peel and slice onions so that they’re in thin strips; set aside.
Heat the butter and oil in a large skillet over low-medium heat. Once the butter has melted, add the onions, stirring to coat them. Reduce heat to a simmer and cook the onions for 15–20 minutes, stirring occasionally so that the onions don’t burn. The onions are done when they are golden in color and most of their liquid is evaporated.
Add Unsweetened Plain Cashewmilk Yogurt to a large bowl, and then pour onions and any leftover oils into the Cashewmilk Yogurt and stir to combine.
Stir in the chopped chives and season to taste with sea salt and black pepper.