Combine flour, baking powder, sugar, and salt in a large food processor. Pulse until fully incorporated. Add in chopped cold butter and process until texture is like coarse crumbs.
Place baking mix in a sealed container and keep in refrigerator. I would try to use it within 6 months, but in my house it would never last that long! You could try to cut the butter in the old fashioned way with a pastry cutter, but I HIGHLY recommend using a food processor it makes it SO much easier. Also, find a good quality sealed plastic container or jar to store, I use one of my larger Lock & Lock containers. Here's links to those products if you want more information:
1 cup baking mix
1/3 cup milk
Place baking mix in medium bowl being sure to break up any large clumps that may have settled. Stir in milk until just moist. Drop on greased cookie sheet and bake at 450 degrees for 10-12 minutes.