Preheat oven to 350°F. Line a standard muffin tin with paper liners.

In a small bowl, whisk together the sorghum flour, white rice flour, potato starch, baking powder, baking soda, cinnamon, allspice, ginger, nutmeg, xanthan gum and salt. Whisk well so that everything is well mixed.

In a large bowl or bowl of a stand mixer, combine the oil, sugars, pumpkin and flax. Beat until smooth and emulsified. Add in have of the milk, beating until smooth. Add all of the reserved flour mixture, and beat just until it starts to mix, and then add the rest of the milk, beating until smooth. Stir in the raisins, if using.

In a small bowl, mix together the 2 tablespoons sugar and a few sprinkles of cinnamon and set aside.

Scoop the batter into the prepared muffin tin. You will be filling them almost to the top, a rounded 3/4 full. Sprinkle the top of each muffin with cinnamon sugar and bake in a preheated oven for 25 to 30 minutes, or until the tops are puffed up with a nice cracked top, are nicely browned and a tester inserted into the center comes out clean.

Let the muffins cool in the tin for 5 minutes before removing to a rack to cool completely.