Preheat your oven to 350°F. Butter a 9 x 13-inch baking dish and set it aside.
Thoroughly wash, peel, and slice the sweet potatoes into ½-inch thick rounds. Place the sweet potatoes in the buttered baking dish and set them aside.
Heat the butter, granulated sugar, brown sugar, cinnamon, ginger, nutmeg, cloves, and salt in a medium saucepan over medium heat just until the butter melts and the ingredients come together. Stir in the vanilla extract and remove the pan from the heat. The sauce will be thick and the sugar will not be fully dissolved.
Pour the butter and sugar mixture over the sweet potatoes in the baking dish and use a wooden spoon or your hands to stir the sweet potatoes and make sure each potato slice is coated in the syrup. This takes some effort but is worth it to avoid dry spots and clumped sweet potatoes. Cover the pan with foil and bake the yams in the preheated oven for 40 minutes.
After 40 minutes, remove the foil from the pan and carefully toss the sweet potatoes, rotating the ones on the bottom and top. This helps make sure all of the potatoes are able to thoroughly absorb that delectable cooking liquid. Continue cooking the yams, uncovered, for an additional 30 to 40 minutes, or until the sweet potatoes can be easily pierced with a fork and the cooking liquid is syrupy. The yams should be very tender but not falling apart.
Allow the candied yams to cool for about 10 minutes in the pan then serve with a slotted spoon. Spoon some additional cooking liquid over top and enjoy!