Scrub the yams clean and cut into 2-inch thick slices. Do NOT peel the yams!
Place yams in a large stockpot and cover with cold water. Place the pot over medium-high heat and bring to a boil.
Allow yams to simmer until fork-tender, about 15 minutes. Carefully drain the water and allow the yams to cool to the touch.
Preheat your oven to 350 degrees F and remove the peels from the yams.
Place yams into a 9-inch x 13-inch baking dish in an even layer. Set aside.
Melt butter in a medium-sized saucepan over medium-high heat
Stir in the brown sugar until combined. Allow to boil for 5 minutes. Pour the brown sugar mixture over top of the yams.
If making ahead of time: cover the baking dish with foil and allow to cool to room temperature before placing it in the refrigerator. Uncover yams before baking.
Place the baking dish in the oven for 30 minutes or until the yams are warmed through and the sauce is slightly bubbling around the edges
Remove from oven. Be careful when serving and the sauce is VERY hot!