Preheat your oven to 400°F. While it heats, peel and cut the yams into 1/2-inch thick rounds (thinner than the original recipe calls for—this helps them caramelize beautifully and cook more evenly). In a small bowl, combine the brown sugar, cinnamon, nutmeg, salt, and pepper. Zest the lemon directly into this spice mixture and set aside. Juice the lemon into a separate small dish for later use.

Melt the butter in a small saucepan over medium heat until just foamy—you want it liquid but not browning. Place the cut yams in a large bowl, then pour the melted butter over them. Add the spice and brown sugar mixture from Step 1, then toss everything together thoroughly until every yam round is evenly coated with butter and spices. I like to use my hands for this—it's the best way to ensure an even coating that leads to beautiful caramelization.

Spread the seasoned yams in a single layer on a baking sheet, arranging them slightly overlapped for even cooking. Roast at 400°F for 35 minutes, tossing the yams halfway through to ensure even browning on both sides. The yams are done when the edges are deeply caramelized and the centers are fork-tender.

Remove the baking sheet from the oven and drizzle the reserved fresh lemon juice over the hot yams, tossing gently to distribute it evenly. The acid from the lemon will brighten the rich caramelized flavors beautifully. Serve the yams hot while they're still at their most tender and the flavors are most vibrant. I find that the heat of the yams helps release the aromatics from the lemon, making the dish even more aromatic.