For sweet potatoes: Preheat oven to 350F. Place 3 pounds sweet potatoes in baking pan and bake until all potatoes are tender, about 1 hour. Maintain oven temperature. Butter 8x8x2" square glass baking dish. Scrap sweet potato pulp from potato skins. Using electric mixer, mash sweet potatoes. Add orange juice, eggs, melted butter, sugar, ground cinnamon, and nutmeg. Beat until sweet potatoes are smooth. Season to taste with salt and pepper. Spoon potatoes into prepared baking dish.
FOR TOPPING: Combine flour, brown sugar, and ground cinnamon in medium bowl. Add butter and cut in until mixture resembles coarse crumbs. Mix in chopped pecans. Sprinkle pecan