1Heat oven to 425°F. Place cookie sheet on middle oven rack. Unroll pie crust in 9-inch glass pie plate as directed on box for One-Crust Filled Pie. In small bowl, mix streusel ingredients. Sprinkle streusel in crust-lined pie plate.
2In large bowl, mix filling ingredients. Pour into pie crust on top of streusel. Place pie plate on cookie sheet in oven. Bake 15 minutes. Reduce oven temperature to 350°F. Bake 35 to 45 minutes longer or until knife inserted in center comes out clean. Cool completely on cooling rack, about 3 hours.
3Just before serving, set oven control to broil. Spread marshmallows evenly over top of pie, completely covering filling. Broil pie with top about 5 inches from heat about 30 seconds, watching carefully, until marshmallows are lightly browned. Marshmallows will brown quickly. Cover and refrigerate any remaining pie.