Serves 8
Prep 30 mins. Bake 55 mins.

Position rack in center of 350 oven

Unroll piecrust into 9" pie pan. Cripple the edge and prick the bottom all over with a fork. Cover the crust with a sheet of foil and fill with dry beans or pie weights. Bake until crust edge is just dry and lightly colored, about 10 mins. Remove the foil and beans.

Meanwhile, pierce the sweet potatoes in several places. Microwave on a paper towel turning once, until they are easily pierced with a fork, about 7 mins. Let cool, then peel.

Using a food processor, pulse the sweet potatoes until smooth. Blend in the buttermilk, then add eggs, brown sugar, and salt and pulse until combined, about 30 seconds. Pour the filling into the pie crust.

Bake until the center is just set, about 50 mins.

Preheat the boiler. Cover the top of the tie with the large marshmallows, mounding then in the middle; fill in empty spaces with mini marshmallows. Place the pie on a baking sheet and broil until browned, less than 1 min. Turn off the broiler, close the oven door and leave the pie in the oven until the marshmallows soften, about 3 mins.

Transfer to a rack to cool.

- Rachel Ray