Can shortening be used instead of butter?

Yes, and it is probably better for you. Shortening is made with hydrogenated fat, which we probably all should try to reduce in our diets.

The results will be a bit different. Butter will add a bit more moisture to your recipe. If you are baking your recipe, such as cookies, you might want to add an egg. The egg will prevent the cookies from spreading too much and add a cake like texture to them, similar to the "crisp outside, chewy inside" results from shortening.