Grease a pudding mold (at least 7 cups, but up to 10 cups will work). Set aside. Combine first 6 ingredients, stirring well with a wire whisk; set aside.
Beat butter at medium speed of an electric mixer until creamy; gradually add sugar, beating well. Add eggs, one at a time, beating after each addition. Mix in pumpkin and pecans. Gradually add flour mixture; mix just until blended.
Pour mixture into prepared mold; cover with lid. Place mold on a rack in a Dutch oven. Add boiling water to Dutch oven to halfway up mold. Bring water to a boil; cover, reduce heat, and simmer 1 hour and 15 minutes or until a wooden pick inserted in center comes out clean.
Remove mold from Dutch oven; let stand, uncovered, 15 minutes. Remove pudding from mold; garnish, if desired. Serve warm with Maple Sauce.