Ingredient

• 4 1/2 pounds sweet potatoes (about 6 medium), preferably Garnet or Jewel
• 1 1/2 sticks unsalted butter, room temperature, plus more for baking dish
• 1/3 cup maple syrup, preferably grade A
• 1 1/2 teaspoons ground ginger
• 3/4 teaspoon ground cinnamon
• 1/4 teaspoon freshly grated nutmeg
• 1/4 teaspoon freshly ground white pepper
• 1 3/4 teaspoons coarse salt

• Step 1

  Sweet potatoes: Preheat oven to 350 degrees. Prick each potato in several places with the tines of a fork. Bake until very soft, 1 to 1 1/2 hours, depending on size. Let stand until cool enough to handle.

• Step 2

  Butter a 9-by-13-inch baking dish. Halve potatoes, scoop out flesh, and transfer to a food processor; puree until smooth. Add butter, syrup, ginger, cinnamon, nutmeg, white pepper, and salt; pulse to combine. Transfer to prepared dish, cover, and bake until hot, about 10 minutes.

• Step 3

  Meringue: Meanwhile, beat egg whites, cream of tartar, and salt on low speed until frothy, about 30 seconds. Increase speed to high; beat until soft peaks form, about 1 minute. Gradually add sugar, beating until thick, glossy peaks form, about 5 minutes. Spoon meringue evenly over potatoes. Holding a small kitchen torch at a 90-degree angle, 3 inches from surface of meringue, move flame back and forth over meringue until it starts to brown. (Or broil 6 to 8 inches from heat source, about 1 minute.) Serve immediately.