– Preheat oven to 350°F, with rack on lower middle position. Whisk half and half, pumpkin, dark brown sugar, eggs, pumpkin pie spice, cinnamon and vanilla extract in large bowl to blend. Fold in bread cubes. Transfer mixture to a lightly greased 9x11 glass baking dish.
– Sprinkle cranberries over top evenly, followed by pecans. Let stand at least 15 minutes to allow bread to soak. Bake until toothpick inserted into center comes out clean, about 40 minutes. Let rest at room temperature until ready to serve (up to overnight, covered. Cover and chill if bread pudding will be sitting out longer than overnight.)
– When ready to serve: whisk brown sugar and butter in heavy medium saucepan over medium heat until butter melts. Whisk in cream and stir until sugar dissolves and sauce is smooth, about 3 minutes. Pour warm sauce over warm/re-warmed bread pudding. Garnish with powdered sugar, if desired.