Test Kitchen Tips:
- To boil sweet potatoes: Peel and cut potatoes into 2-inch chunks. Place in large saucepan. Add cold water to cover 1 inch over potatoes. Bring to boil. Cover and and cook on medium-low heat 20 to 30 minutes or until tender. Drain.
- To use canned sweet potatoes: Use 2 cans (29 ounces each) sweet potatoes, drained, in place of the fresh sweet potatoes. Continue with Step 2.
Preheat oven to 350°F. Pierce each potato twice with a fork so excess steam can escape while cooking. Microwave potatoes on HIGH 5 to 10 minutes or until tender, turning potatoes over halfway through cooking. Let stand 5 minutes or until cool enough to handle. Remove skin from potatoes.
Place potatoes, brown sugar, cream, butter, vanilla and pumpkin pie spice in large bowl. Beat with electric mixer on medium speed until smooth and fluffy. Spoon mixture into greased 13x9-inch or 3-quart baking dish. Top with marshmallows.
For the Streusel, mix flour, brown sugar and pumpkin pie spice in medium bowl. Cut in butter with pastry blender or 2 knives until crumbly. Stir in pecans and coconut. Sprinkle over top.
Bake 25 minutes or until heated through and topping is golden brown.