Peel and chop 3 pounds celery root. Peel, halve and core 2 Bosc pears. Combine the celery root and pears in a saucepan with 3 cups milk, 1 smashed garlic clove and enough water to cover; simmer until tender, 25 to 30 minutes. Drain, reserving the liquid. Puree in a blender until smooth, adding the reserved liquid as needed. Season with salt and pepper. Cover and refrigerate overnight. When ready to serve, brown 3 tablespoons butter in a saucepan over medium heat. Add 1/4 cup parsley and fry 2 minutes. Microwave the puree to warm and top with the browned butter.