Mix the dry ingredients into a bowl. Cut the butter or margarine into small portions and rub into the mixture with your fingers. Add the sugar and mix well. Slowly add enough milk (you may not need the full half cup) and mix until you have a stiff but workable dough. If the dough is too wet, simply add a little more flour or oatmeal.
Flour a clean work surface before placing the dough out to roll. Sprinkle a little flour on the top, and roll to 1/2" thickness, 1/4' if you like a more crispy cakes.
Cut into the size of your choice: Use a 2" biscuit cutter make dainty size for tea or cocktails, a 2½" or 3" cutter for a more substantial size.