- 1 tablespoon olive oil
- 3 large white onions, thinly sliced
- 2 tablespoons brown sugar
- 1/4 teaspoon salt
- 3 baking potatoes (such as Yukon gold, about 2 pounds), peeled and cubed
- 6 parsnips (about 1 lb), peeled and cut into 1-inch pieces
- 1 1/2 cups low-sodium chicken broth, heated
- 1/4 cup crumbled blue cheese
- 3 tablespoons fresh thyme, chopped
- Heat oil in a large skillet over high heat; reduce to medium. Cook onions with sugar and salt, stirring occasionally, until onions brown, 20 to 25 minutes. Add a few tablespoons water as you cook to keep onions from sticking or burning. Fill a medium stockpot ¾ full with cold water. Add potatoes and parsnips; bring to a boil over high heat. Reduce heat and simmer until potatoes and parsnips are fork-tender, 20 to 25 minutes, then drain. Beat 1/4 of potato parsnip mixture and 3 ounces broth in a mixing bowl with an electric mixer on medium speed until smooth. Repeat, alternating between potato-parsnip mixture and broth, until you've incorporated all. Fold in onions, cheese and thyme, and serve.