It comes from the Better Homes and Gardens 14th edition cookbook, which is awesome, by the way.
What was the most useful about this cookbook is it explained how to substitute buttermilk and get the same results. apparently buttermilk is acidic, and in recipes with buttermilk there is also baking soda, and when those acid and baking soda collide there is that volcano action from our science project youth. so to subsitute you want to put one tablespoon of acidic liquid like lemon juice or vinegar into a glass measuring cup or a one cup measuring cup. then add enough milk to make one cup total. (not a cup and tablespoon, but a cup of combined liquid total). Rice milk works fine, thats what I use. let sit for 5 minutes.
3 cups all purpose flour (but I do half and half all purpose and half whole wheat successfully)
1 tablespoon baking powder
1 tablespoon sugar
1 teaspoon salt
3/4 teaspoon cream of tartar (just give up substitution and buy it)
3/4 cup cold butter (I found out you want it cold, cause I used to melt it and add it, so that when the butter melts in the dough while cooking it releases steam causing the flaky layers)
1 and 1/4 cups sour milk
this is a wet dough by the way
Preheat oven to 450 deg.
combine dry ingredients. (1-5)
cut up butter and add into dough. you can use a pastry blender, or two knives I have heard you can use, I rub it in with my fingers until its all flour/butter granuals.
make a well in center and add milk
stir until moistened. its pretty wet.
flour your board and kneed it a few times and pat it out until its about 3/4 inch thick (I guess) and cut out biscuits with a cutter or in my case a cup rim. cook for 10-14 minutes.
This recipe should cook about 12 biscuits. I always cut it in half.
some things I have found out or heard:
don't kneed them too much or they get ruined. I don't know the consequences, and I also don't know how much is too much. I've heard that from multiple sources.
secondly don't oil your baking sheet. I have done this. my bottoms cooked way faster, I think.
The recipe says not to do this, but I was scared of them sticking so I did it anyway. you don't need to.