3poundssweet potatoes peeled and chopped into large chunks
1/4cupwhole milk or half and half
4tablespoonsunsalted butter, softened
Preheat oven to 375°F. Grease a 2-quart casserole dish and set aside.
Place the sweet potatoes in a large pot, cover with water, and boil until tender (about 7 minutes, depending on the size).
Drain and return to the pot. Add butter, milk, cinnamon, brown sugar, maple syrup and salt to the potatoes and mash until smooth. Use a hand mixer, if desired, to make them extra smooth. Taste the potatoes and add additional seasonings, if desired.
Transfer the mashed potatoes to the prepared casserole dish. Place in the oven until heated through - if they're warm it will only take a few minutes.
While the sweet potatoes are heating, prepare the topping. In a medium bowl, combine butter, brown sugar, flour, cinnamon, salt, and pecans. Stir until thoroughly combined.
Remove the sweet potatoes from the oven. Top with half the marshmallows, then sprinkle half the streusel over the marshmallows. Top with the other half of the marshmallows and sprinkle the remaining streusel over the top.
Place back into the oven for 10-15 minutes, until the topping is bubbly and brown (keep an eye on it so the marshmallows don't burn).