• Preheat oven to 350 degrees. In a medium baking dish, spray with non-stick cooking spray. Set aside. (An oval or rectangular baking dish is ideal (about 9 - 10").
• Wash, peel, and but the sweet potatoes into 1" pieces. Bring to a boil over medium high heat. Cook until fork-tender. (Depending on how large or small they are cut, this takes 14-18 minutes.) To test the potatoes for doneness, pierce with a fork or knife. If the potato piece breaks apart easily, they are done.
• Transfer the cooked potatoes to a mixing bowl or keep in the original saucepan. Add the brown sugar, half and half, butter, egg, vanilla and salt. Using a potato masher, combine the ingredients and mash until mostly smooth. Small lumps are okay. Transfer the potato mixture to the prepared baking dish. Smooth out evenly. Bake the casserole uncovered at 350 degrees for 35 minutes.

Pecan Topping:

• While the casserole bakes, prepare the pecan topping. In a mixing bowl, combine the brown sugar, pecans, flour, cinnamon and nutmeg. Stir together to combine. Pour the melted butter into the brown sugar mixture, and stir until crumbly.
• Once the casserole has baked for the 35 minutes, remove from oven. Top the casserole with half of the pecan crumble. Then add the mini marshmallows over the top of the pecan crumble. Finish with the remainder of the pecan crumble. (Layering the pecan crumble and marshmallows allow both toppings to cover the casserole evenly and will allow the pecans to toast and the marshmallows to lightly brown.)
• Bake for another 10-15 minutes at 350 degrees to allow the pecans to toast and the marshmallows to lightly brown.
• Remove from the oven and let the casserole cool at least 10 minutes before serving.