Heat oven to 350 degrees F. Coat 2 (9x5-inch) loaf pans with no-stick cooking spray.
Combine flour, baking powder, baking soda, pumpkin pie spice and salt. Beat pumpkin, oil, sugar and eggs in bowl with electric mixer until well blended. Add dry ingredients; mix well. Divide batter between prepared loaf pans.
Bake 50 to 55 minutes or until toothpick inserted in center comes out clean. Turn oven to broil. Sprinkle marshmallows evenly over breads. Broil 3 minutes or until marshmallows are lightly browned. Cool completely.