Pumpkin Pie Muffins

-1 cup whole wheat flour

-1/2 cup white flour

-3/4 cup light brown sugar

-1 tsp. baking powder

-1 tsp. baking soda

-1 tsp. pumpkin pie spice

-Pinch of salt

-15 oz. pumpkin puree

-1/2 cup vegetable oil

-1/4 cup soy milk

-2 large eggs

-1/2 tsp. vanilla extract

-1/2 cup chocolate chips, optional

-Cinnamon and sugar, to sprinkle