Preheat oven to 375 degrees F. Line a large baking sheet with foil. With paring knife, poke holes all over the sweet potatoes and place on baking sheet. Roast 40-50 minutes, until knife easily pierces through potato, turning occasionally. Remove from oven and let cool.

Meanwhile, drain the pineapple through a strainer, pressing out excess liquid.

Increase oven temperature to 425 degrees F. When cool enough to handle, peel sweet potatoes and place in a large bowl, along with brown sugar, maple syrup, cinnamon and drained pineapple. Season with salt. With potato masher, mash until smooth.

Transfer sweet potato mixture to 3-quart baking dish, spreading the top to smooth. Top with the marshmallows. Bake 8-10 minutes, until marshmallows are golden brown and puffed. Remove from oven and serve.

Tip: To make this ahead, assemble the casserole up to 1 day in advance and refrigerate. Bake at 400 degrees F for 20 minutes.