If you're making a pie crust or a pastry of some kind, there is a reason of sorts for the two together-- butter makes a flaky crust/pastry~ shortening will make it more tender, by using both it will make a flaky tender crust.. Now if I was you and if you use this than I would just sub out the shortening for lard, or I have used only butter and it works fine too.. just use 1/2 the amount of the butter at room temp and 1/2 very, very cold.. it will do almost the same as the shortening. Cold butter will make it flaky and warm butter will absorb more and make it a bit more tender(not as tender as that fake stuff, but better for you).