Wash the yams and prick with a fork. Place on a baking tray and bake at 400°F for 1 hour, or until soft when gently squeezed.
Cut in half lengthwise and carefully scoop the flesh out into a bowl, being careful not to break the skins. Add the butter and mash well. Add the thyme, chives, salt, and pepper to taste and mix well.
Spoon the mixture back into the skins, piling up slightly in the center. Mix grated cheese and chili garlic sauce. Then top yams with this and return to the oven for about 10 minutes, or until the cheese is melted and the yams are heated through.
If you are concerned about the spice, you can leave off the chili sauce for a delicious stuffed yam.
Just like a potato, it is important to poke holes in it before baking. This allows the yam to cook all the way through.
If you are worried about breaking the skin when scooping the inside out, you can hold the yam with a cloth to help control it a little bit better.
This recipe is a variation of a recipe I got from wai Lana yoga. Thanks to Burgundy_sal for sharing it with me.