In a small saucepan over medium-high heat, melt the butter and add the garlic. When the garlic has browned, add the onions. Cook the onions until slightly caramelized, about 3 to 5 minutes. Stir in the flour and the chipotles and cook for an additional minute. Pour the cream and stock into the pan and stir. Season with salt and pepper, to taste. Bring the mixture to a simmer, stirring occasionally.
Layer about 1/3 of the yam slices in a well greased 11-inch baking dish. Drizzle 1/3 of the cream sauce over the yams and sprinkle some cheese on top. Repeat the steps, reserving 1/4 cup of the cheese.
In a small bowl, mix together the bread crumbs, reserved cheese and parsley. Set aside.
Cover the yams with foil and bake in the oven for 30 minutes. Remove from the oven, discard the foil and top with the bread crumb mixture. Return to the oven for an additional 15 minutes. Remove from the oven and allow to sit for 5 minutes before serving. Garnish with chopped parsley and serve.