4-5large (4 pounds)sweet potatoes (I use Garnet or Jewel variety)
1/4cupbrown sugar,I use dark brown, but light works great too
1/4cupgranulated white sugar
4tablespoonsunsalted butter
1teaspoonvanilla extract
1/2cupevaporated milk(1%, 2%, or whole milk will work ok)
1teaspoonground cinnamon,optional
1/2teaspoonsalt
2largeeggs
Pecan/Marshmallow Topping
4tablespoonsunsalted butter,melted
3/4cupchopped pecans
1/2cupbrown sugar,I use dark brown, but light works great too
1/2cupwhite all-purpose flour
1/4teaspoonsalt
1.5 - 3cupsminiature marshmallows
Instructions
Preheat oven to 400 degrees F. Wash and deeply pierce each sweet potato several times with a fork and transfer to a foil-lined large baking sheet. Bake 1 hour, or until very tender when pierced with a fork. Once fork tender, remove from the oven, allow to slightly cool, and then cut potatoes in half and pull off the skins (they should slip right off!)
If the skins don't come off easily, scoop out the flesh from the halved potatoes. Place into a large mixing bowl and mash the potatoes with a potato masher. Add in brown sugar, white sugar, butter, vanilla, evaporated milk, cinnamon, and salt. Blend, using an electric hand mixer on low speed until smooth. Add in eggs and beat until blended and smooth. Reduce oven temperature to 350 degrees F.
Smooth the sweet potato mixture into a 9x13-inch pan. In a separate bowl, combine the pecan topping: the melted butter, chopped pecans, brown sugar, flour, and salt. Stir until ingredients are well incorporated. Either top the entire casserole with this mixture or top in rows. If you opt to do rows (as pictured) you'll have about 1/2 cup extra of the topping; if you top the entire casserole, you'll use all of it. Bake in a 350-degree oven for 30 minutes (tent with foil if streusel is browning too quickly).
Remove casserole and add marshmallows (to desired preference) over the casserole -- either on top of the pecan topping or in between rows. If in between rows, you'll use about 1 and 1/2 cups. If you top the whole casserole, about 3 cups. Return to the oven and bake for 4-8 minutes or until marshmallows are melty and lightly golden (watch carefully!). Remove from oven and serve warm.
MAKE IN ADVANCE: You can make this casserole in advance by following these tips: store the pecan topping and marshmallows separately. Cover the sweet potato casserole tightly and refrigerate. When ready to bake, add pecan topping and place in the oven while it's preheating; continue to bake for 25-30 minutes once preheated. Add marshmallows according to recipe instructions.