Preheat the oven to 400 degrees. Line 2 muffin tins with liners (9 liners in each tin).
In a large bowl combine the gluten free flour blend, rice flour, baking powder, cinnamon, baking soda, salt, and sugar.
In a medium bowl combine the applesauce, yogurt, milk, oil, eggs, vanilla, and lemon extract.
Whisk until combined.
Pour the liquid ingredients into the dry ingredients and stir until well combined. The batter will be very thick.
Carefully fold in the blackberries. Fill 18 muffin cups 2/3 of the way full with the batter.
Sprinkle the tops with sugar if desired.
Bake the muffins for 20 minutes. Remove from oven and set the muffin tins on a wire rack to cool completely.