Bisquick

This stuff is way cheaper than the store-bought stuff, and it is amazingly useful if you like biscuits or muffins, or pancakes or anything like that.

6 cups flour
3 Tbsp baking powder
1 Tbsp salt
1 cup cold unsalted butter or shortening

Mix the flour, baking powder, and salt. Cut in butter until thoroughly incorporated. Store refrigerated for up to 4 months.

To make biscuits, mix 2 1/4 cups of bisquick with 2/3 cup milk (or water...but milk definitely tastes much better) until you have a soft dough. Roll the dough out to about 1/2" thickness on a floured surface. Cut biscuits with a 2 1/2" cutter (you can use a cup), or cut into 2 1/2" squares. Place on an un-greased baking sheet and bake at 450 degrees for 8-10 minutes, until golden brown.