Step 1

Preheat the oven to 350°F. Grease an 8”x10” casserole dish (8×8 or 9×9 works too).

Step 2

Fill a large pot with sweet potato pieces and enough water to cover by 2 inches. Bring to a boil over high heat and cook until fork tender, about 10 minutes.

Step 3

Drain water from potatoes and return potatoes to the pot. Using a potato masher or electric mixer, mash until mostly smooth. Add remaining ingredients (except topping ingredients and mix until combined.

Step 4

Spoon sweet potatoes into the casserole dish and use the back of a wooden spoon or mixing spatula to smooth out. Sprinkle marshmallows over top of mashed sweet potatoes.

Step 5

Add butter to a medium sized microwave safe bowl. Microwave on full power to melt the butter. Add remaining topping ingredients to the bowl, and use a fork to combine. Sprinkle over the top of casserole.

Step 6

Place the casserole in the preheated oven and bake for 20-25 minutes, or until the streusel is crisp and marshmallows are golden brown.

Step 7

Serve while warm, and enjoy!