In a large mixing bowl, whisk together the flours, sugar, baking powder, and salt.
Using a pastry blender, cut the butter into the dry mixture until it is about the size of small peas.
In a small mixing bowl, whisk the egg and milk together. Stir this mixture into the dry ingredients just until they are combined. Add the raisins, if you are using them.
On a floured surface with a floured rolling pin, roll out the dough until it is about ½ inch (1.27cm) thick. (Use any of the flours that are in the recipe. I usually use rice flour for this.) Cut with sharp cookie cutter about 2 inches (5.08cm) in diameter and place ¼ inch (0.635cm) apart onto a greased or parchment-lined baking sheet.
Bake for 15 to 18 minutes until biscuits are just starting to brown around the edges at the bottom.