Preheat oven to 425 degrees F. In a 2-quart square baking dish or 8x8x2-inch baking pan place the sweet potato, carrot, onion, and garlic. Drizzle with oil and toss to coat. Cover with foil.
Bake for 20 minutes. Remove foil; stir vegetables. Bake, uncovered, for 10 to 15 minutes more or until vegetables are tender.
Transfer vegetables to a food processor. Add ginger, salt, and the dash black pepper. Cover and process just until coarsely pureed, adding 1 to 2 tablespoons milk as necessary for desired consistency. If desired, garnish with additional black pepper.