Preheat oven to 325 degrees F. Prick each yam several times with a fork and set in a parchment paper-lined baking pan. Bake until just tender, about 60 minutes. Cool the yams to room temperature. Line a baking sheet with parchment paper. Slice the yams into 1/2" thick rounds and set on the baking sheet. Combine the remaining ingredients, except parsley, in a bowl and brush over the tops of the yams. (Yams can be prepared to this point several hours in advance and stored in the fridge until ready to bake). Bake the yams, uncovered, in a 325 degrees F oven for 20 minutes, or until heated through. Sprinkle with parsley and serve.