Place potatoes in a small stockpot. Add cold water to cover potatoes by 1 inch. Bring water to a boil over high heat. Reduce heat to medium and simmer 20 minutes, or until potatoes are fork-tender.
While the potatoes are cooking, combine the milk, scallions, salt and pepper in a small saucepan. Bring the mixture to a simmer over medium heat, stirring occasionally. Remove from the heat and set aside.
When potatoes are done, drain them, but do not rinse them. Return potatoes to the stockpot and mash with a potato masher. With a wooden spoon, stir in the milk mixture until well combined.
To serve, divide the champ between four dinner plates, making each portion into a tall mound. Using the back of a teaspoon, make a small well at the top of each mound. Carefully pour 1 tablespoon (15 ml) melted butter into the well on each portion.
Per serving: 412 calories, 36 mg cholesterol, 289 mg sodium, 8 g protein, 13 g fat, 67 g carbohydrates