Preheat the oven to 350 degrees F. Prick each yam a few times with a fork and set on a baking sheet. Bake 60 to 70 minutes, until just tender, but still slightly firm in the centre. Cool the yams until safe enough to handle, but still warm. Pull off the skins with a small knife. Coat the bottom of a 9" x 13" baking dish with 1 1/2 Tbsp. of the butter. Slice the yams into 1/2" thick rounds and place in slightly overlapping rows in the baking dish.
Melt the remaining butter in a skillet set over medium heat. Add the onion and apple and cook until softened, about 5 minutes. Remove from the heat and stir in the lemon juice, honey and spices. Spoon the mixture over the yams. Pour in the stock and season with salt and pepper. (The yams can be prepared to this point a few hours in advance. Refrigerate until ready to bake and serve. Add a few minutes to the baking time, as they will be cold.) Cover the yams with foil and bake for 30 minutes, or until heated through and tender. Sprinkle with almonds and parsley and serve.
Note: To toast the almonds, set in a single layer in a skillet. Cook over medium heat, swirling the pan occasionally, until lightly toasted, about 5 minutes.