Preheat oven to 400 degrees F. Line sixteen 2-1/2-inch muffin cups with paper bake cups; set aside. In a medium bowl stir together flour, brown sugar, granulated sugar, baking powder, cinnamon, ground ginger, and salt. Make a well in the center of the flour mixture; set aside.
In a small bowl stir together the pumpkin, melted butter, buttermilk, and eggs. Add egg mixture all at once to flour mixture. Stir just until moistened (batter should be lumpy). Spoon batter evenly into prepared muffin cups.
Bake for 18 to 20 minutes or until a wooden toothpick inserted in the centers of muffins comes out clean. Remove muffins from muffin cups; cool completely on a wire rack.
Dip the tops of the muffins into the Chocolate Glaze, allowing excess glaze to drip off. Place dipped muffins upright on the wire rack. Sprinkle tops of muffins with chopped crystallized ginger. Let stand for 30 minutes or until glaze sets.