In a large mixing bowl sift together Sun Flour Mills Pastry Flour, sugar, salt, baking powder, xanthan gum.
In a separate bowl cream together butter and sugar. Add egg and vanilla to the creamed mixture until incorporated.
Alternate adding in milk and dry mix to the creamed mixture. Mix until incorporated.
Gently fold in blueberries.
Divide evenly between 12 muffin tins. Fill batter 3/4 of the way to the top of the muffin tin.
Bake at 400 degrees for 20-25 minutes