Preheat the oven to 400°F. Line 6 regular muffin tins with paper baking cups or lightly coat the bottoms only with vegetable cooking spray.
In a medium bowl, combine the flour, 1/2 cup (8 tablespoons) oats, 1/4 cup (4 tablespoons) brown sugar, baking powder, baking soda, 1/2 teaspoon cinnamon, nutmeg, allspice and salt (if using).
In a small bowl, whisk together the pumpkin, egg, milk, and margarine. Make a well in the center of the dry ingredients and add the pumpkin mixture, Mix just until the dry ingredients are moistened. Do not overmix.
Spoon the batter into the prepared muffin cups, filling almost full.
To make the topping, mix together the remaining 2 tablespoon of oats, remaining 1/2 tablespoon brown sugar, orange zest, and 1/8 teaspoon of cinnamon; sprinkle evenly over the top of each muffin.
Bake for 22 - 25 minutes, or until a tester inserted in the center comes out with only a few moist crumbs attached. Cool the muffins in the pan on a wire rack for 5 minutes before removing. serve warm.