Line a baking sheet with foil and lay the sweet potatoes on top. Pierce a few times with a fork.
3 Pounds Sweet Potatoes
Bake in the oven for about 45 minutes (maybe more if the potatoes are larger).
Remove from the oven and allow to cool for 5 minutes then using a paper towel pinch the sweet potato skin off the potato. It should come off relatively easy.
Place in a bowl and mash the sweet potatoes with a potato mashed.
Add the melted butter and mash again.
⅓ Cup Unsalted Butter
Add the spices, brown sugar and half and half and mash again.
½ Cup Light Brown Sugar, 1 teaspoon Cinnamon, ¼ teaspoon Nutmeg, ¼ teaspoon Ginger, ½ teaspoon Vanilla Extract, ½ teaspoon Salt, 2 Tablespoons Half and Half
Spread into a greased 9x9" baking dish and set to the side.
Add the egg whites and cream of tartar to the bowl of a stand mixer and whip, using the wire whip attachment on high, until soft peaks have formed.
½ Cup Egg Whites, 1 teaspoon Cream of Tartar
While that happens, add the water, sugar, honey and salt to a small pot on the stove and heat over medium-high heat, stirring.
⅓ Cup Water, ⅓ Cup Granulated Sugar, ¾ Cup Honey, ¼ teaspoon Salt
Bring to a boil then reduce the heat to allow a slow boil. Allow to boil (without boiling over) for 10 minutes. Stirring often.
With the mixer on low, slowly pour this hot syrup into the egg whites, then add vanilla.
1 teaspoon Vanilla Extract
Turn the mixer on high and allow to whip up for about 6-8 minutes. The egg whites will become a lot 'more' and will glossy with stiff peaks.
Spoon this marshmallow mixture on top of the sweet potatoes (there will be a lot left over).
Using a kitchen torch, lightly torch the top of the marshmallow for a toasty look.
Notes
I like to use honey in my marshmallow topping - it adds a different, kind of seasonal flavor to it. If you don't like that though, you can use the traditional light corn syrup.This recipe will yield a lot of extra marshmallow. You could double up on the sweet potatoes layer and make a 9x13" casserole with the same amount of fluff.