1/2 cup unsalted butter, at room temperature
1 cup packed brown sugar
2 large eggs
1 tsp vanilla extract
1/2 tsp salt
1 tsp ground cinnamon
1/8 tsp nutmeg
1/8 tsp ground ginger
1 1/2 cups all-purpose flour
half of a 10.5 oz bag of mini marshmallows
Preheat the oven to 400 degrees. Scrub the sweet potato and poke a few holes in the top with a fork. Bake 45 min to an hour, until it is cooked through and soft. Remove from oven, allow to cool until it is cool enough to handle, then peel and mash with a fork until smooth. Measure out 3/4 cup of the puree and set aside.
Decrease the oven temperature to 350 degrees. Spray miniature muffin pan with cooking spray.
In a bowl, cream the butter and sugar at medium speed until light and fluffy, 3 to 5 minutes. Add the eggs, one at a time, scraping down the bowl as needed. Mix in the vanilla and the salt, cinnamon, nutmeg, and ginger. With the mixer on low, slowly add the flour, and mix until just incorporated. Using a rubber spatula, fold in the sweet potato puree.
Pour the batter into the prepared pan and bake 26-30 minutes, or until a toothpick inserted into the center comes out clean. Scatter the marshmallows over the top, being sure to cover the entire pan. Preheat the broiler, and broil the bars until the marshmallows are dark golden-brown. You may have to rotate the pan a few times depending on how evenly your broiler cooks.
Remove from oven and allow to cool to room temperature before taking muffins out of the pan.
Source: Pink Parsley