Place the potatoes into a medium-sized pot. Add enough water to cover the potatoes and bring to a boil over high heat. Reduce the temperature to medium and cook until the potatoes are tender when pierced with a fork, about 20 minutes.

Drain the potatoes and return them to the pot. Add the heavy cream, 3 tablespoons of butter, salt, and pepper. Mash with a potato masher. Fold in the green onions.

Transfer the potatoes to a serving dish. Make a well in the center and place the remaining 2 tablespoons of butter in the well. Serve once the butter has melted.