celeriac & potato mash

  • 1 pound celeriac, peeled, cut into 1/2-inch pieces (about 4 cups)
  • 2 1/2 pounds potatoes, peeled, cut into 1-inch pieces (about 6 1/2 cups)
  • 1/4 cup (1/2 stick) unsalted butter, cut into pieces
  • 1/2 cup (or more) whole milk
  • 1/4 cup chopped celery leaves

Cook celery root in large pot of boiling salted water 5 minutes. Add potatoes to pot and cook until all vegetables are tender, about 20 minutes. Drain and return vegetables to pot; stir over medium-high heat until dry, 1 to 2 minutes. Remove from heat and add butter. Using potato masher or a hand blender, mash vegetables until butter is incorporated. Add 1/2 cup milk and mash until almost smooth, adding more milk as needed. Stir in celery leaves. Season with salt and pepper.