Yam and Pineapple Pudding

PUDDING

4 pounds orange-fleshed (Louisiana or jewel) yams (about 5 large yams), scrubbed
4 tablespoons (½ stick) unsalted butter
½ cup heavy cream
½ cup packed light brown sugar
One 20-ounce can crushed pineapple, drained well
4 large eggs, at room temperature, separated
½ teaspoon ground cinnamon
½ teaspoon ground cloves
Grated zest of 1 lemon

TOPPING

Yams are the orange-fleshed tubers that many people call sweet potatoes, but, in fact, sweet potatoes are yellow fleshed and not very sweet at all.

To make the pudding, place the yams in a large pot and add enough water, lightly salted, to cover. Bring to a boil over high heat. Reduce the heat to medium and partially cover. Cook at a brisk simmer until the yams are tender when pierced with the tip of a knife, 30 to 40 minutes. Drain and rinse under cold water until cool enough to handle. Peel and place in a large bowl.
Position a rack in the center of the oven and preheat to 350°F. Lightly butter a deep 21 /2-quart casserole.
In a large bowl, using an electric mixer on low speed, mash the yams with the butter. Add the heavy cream and brown sugar, beating to dissolve the sugar. Add the crushed pineapple. One at a time, add the yolks, beating well after each addition, then mix in the cinnamon, cloves, and lemon zest. (The pudding can be prepared to this point up to 2 hours ahead, loosely covered with plastic wrap and stored at room temperature.)
In a medium bowl, using clean beaters, beat the egg whites at high speed until soft peaks form. Stir about a quarter of the whites into the pudding, then fold in the rest. Transfer to the prepared dish and spread evenly.
To make the topping, in a small bowl, using your fingers, work together the brown sugar, flour, and butter until combined, then work in the pecans. Sprinkle over the pudding.
Bake until the pudding is slightly puffed and lightly browned, about 1 hour. Serve immediately.