Pecan Sweet Potato Casserole

From Cook’s Illustrated

3 pounds sweet potatoes or yams, peeled, cut into 1-inch cubes
6 tablespoons butter, melted
5 tablespoons maple syrup
1 teaspoon powdered ginger
1 teaspoon salt
1/8 teaspoon cayenne, or to taste
1 1/2 tablespoons arrowroot powder

Pecan Topping
1/2 cup pecans, chopped
6 tablespoons brown sugar
1/4 cup flour
4 tablespoons cold butter, cut into small cubes

Heat oven to 375°F. Parboil the sweet potatoes in salted boiling water until soft but not falling apart, about 6 minutes. Drain and spread in a greased 13 x 9 baking dish.

Topping instructions:

1. Whisk brown sugar and flour together in a bowl. Add the butter and toss. Smash butter cubes with a fork and mix with flour mixture until it resembles coarse corn meal. Stir in pecans and refrigerate until ready to use.
2. Whisk melted butter, maple syrup, ginger, salt, and cayenne in a bowl. Mix arrowroot with 2 tablespoons cold water in a separate bowl until smooth and then whisk into butter mixture. Pour over sweet potatoes and toss to coat. Cover pan with foil and bake for 30 minutes. Remove foil and stir potatoes gently. 
3. Sprinkle topping mixture over potatoes and bake until topping is crisp and golden, about 20 minutes. Serves 8 – 10.