Step 1

Arrange a rack in the middle of the oven and heat the oven to 400°F. Meanwhile, peel and cut 2 1/2 pounds yams into 1-inch cubes and place in a large bowl. Finely grate the zest of 1 medium lemon into the bowl. Halve the zested lemon and set aside for later.

Step 2

Melt 1 stick unsalted butter in the microwave or on the stovetop, then pour over the yams. Add 1/2 cup packed light brown sugar, 1/2 teaspoon ground cinnamon, 1/2 teaspoon ground nutmeg, 1 1/2 teaspoons kosher salt, and 1/4 teaspoon cracked black pepper. Toss until evenly coated. Transfer the yams to a rimmed baking sheet and spread into a single layer.

Step 3

Roast until tender and lightly caramelized, tossing halfway through, about 35 minutes total. Remove the baking sheet from the oven. Immediately squeeze the juice from the lemon halves all over the yams and toss. Serve hot.