Step 1: You will need some sort of good mixer. Make sure you use beaters when making the mix as shown above. If you don't have a good mixer, start calling around...get together with a friend and make some...it is SOOOO worth it!
2 1/3 C. Powdered Milk
1 C. All Purpose Flour (Yes, use All Purpose)
1 C. (2 sticks) Margarine (***HAS TO BE REAL MARGARINE, NOT SPREAD***) or Butter, at room temperature
Combine dry milk, flour and margarine/butter into a large bowl.
Step 3: Mix until it looks like corn meal. (You may want to start off slow and work up to the fastest setting so that it doesn't blow powder all over)
Step 4: Keep mix tightly covered in the refrigerator. (note: keep your #10 cans for just such a purpose! They are 50 cents and work great for storing home made mixes)