Preheat the oven to 350 F degrees.

Prick the potatoes with a fork and place them on a pan. Bake the potatoes until tender, 45 minutes to an hour (a knife or fork should go in easily when the sweet potatoes are done baking). When the potatoes are cool enough to handle, cut them open, scoop out the insides and place the potatoes in a large bowl.

Add the butter, milk, brown sugar, maple syrup, cinnamon, vanilla and salt to the bowl.

Mash Potatoes: Use a potato masher or hand mixer to mash or beat the potatoes until mostly smooth. I started with a potato masher and switched to a hand held mixer.

First Bake: Grease a 9-inch square pan or 2-quart baking dish with cooking spray. Spread the sweet potato mixture evenly in the pan. Bake for 15 minutes.

Prepare the topping. In a medium bowl, combine butter, brown sugar, flour, cinnamon, salt, and pecans. Stir until thoroughly combined.

Top Potato Mixture: Once you pulled the sweet potato out the oven, top the sweet potato mixture 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. Add Tip Ask Question Comment Download Second Bake: Place back into the oven for 8-15 minutes (I placed my baking dish onto a cookie sheet to avoid a mess), until the topping is bubbly and brown. You can also place your oven in the broil setting and allow it to broil for the last 2-3 mins.