Preheat oven to 350.Peel, then chop the yams (about 1/2 inch thick).Place the yams into a 9x13 bake dish.
Place the butter into a medium sized pot, then melt it over medium heat.Once the butter is melted, sprinkle in the white & brown sugar, ground cinnamon,ground nutmeg, ground ginger, and ground clove.Turn the stove off, mix the ingredients, then add in the vanilla extract.
Pour the candied mixture over the yams, and try to coat all the yams with the mixture. Next, cover the bake dish with foil, then bake the yams in the oven for 30 minutes.Remove the yams from the oven, and baste them with the candied mixture.Cover the yams, and bake them for another 15-20 minutes.**During the last 3-4 minutes, add the marshmallows until browned (optional)
Remove the yams from the oven, and let them sit for about 10 minutes before serving.ENJOY!