3 tablespoons butter + 2 tablespoons extra-virgin olive oil OR 5 tablespoons olive oil
2-1/2 pounds onions, thinly sliced
2 teaspoons brown sugar
1/4 teaspoon each salt and pepper
Melt the butter with the olive oil (or simply warm the oil) over medium-high heat in a large skillet. Add the onions and 1/4 teaspoon each salt and pepper and cook, stirring constantly, until the onions begin to soften, about 5 minutes. Add the brown sugar and stir thoroughly. Continue to cook, scraping the browned bits off the bottom of the pan frequently, until the onions are soft and golden brown, about 20 minutes.