No Fat Chocolate Muffins

1 1/3 cups flour
1 cup sugar
1/3 cup unsweetened cocoa powder
1 1/4 tsp baking soda
2 tsp baking powder
3/4 cup non fat plain yogurt
3/4 cup skim milk
1 1/2 tsp vanilla
1/4 tsp cinnamon

combine all dry ingredients and mix well in another bowl blend all wet ingredients add wet mixture to the dry ingredients and mix just until blended. spoon into well greased muffin cups 
bake in 400 degree oven for 15-20 minutes