Ingredients
1 medium celery root (also called celeriac; about 14 ounces), peeled and cut into 1/2-inch dice
1 fresh thyme sprig, plus more for garnish
1 garlic clove, crushed
Coarse salt and freshly ground pepper
1 small russet potato (about 9 ounces), peeled and cut into 1/2-inch dice
1/4 cup whole milk
2 tablespoons unsalted butter, plus more for serving
Preparation
Put celery root, thyme sprig, and garlic into a small saucepan. Cover with cold water by 1 inch. Bring to a boil. Reduce heat; add 2 teaspoons salt and the potato. Simmer until vegetables are very soft, about 10 minutes.
Drain; discard thyme sprig. Transfer vegetable mixture to a food processor. Add milk and butter, and process until just pureed. Season with salt and pepper. Garnish with thyme. Serve with a pat of butter.
