Celery Root Puree

Name: Celery Root Puree
Yield: 6 Servings
Ingredients: 3 cups whole milk; 3 cups water; 1 tablespoon salt; 2 large celery roots (about 2 1/2 pounds total), peeled, cut into 2-inch cubes; 1 medium russet potato (about 10 ounces), peeled, cut into 2-inch cubes; 1 small onion, peeled, quartered; 5 tablespoons butter, cut into 5 pieces; Ground white pepper; Chopped fresh chives