Preheat oven to 350° F. and grease 2 cookie sheets. Cream shortening; add sugar gradually, creaming until light and fluffy. Add cream cheese and half the egg, and blend well. Sift flour, Rumford Baking Powder, and salt together. Add to creamed mixture, mixing well. Shape in roll, wrap in waxed paper and chill in refrigerator. Drop cookie dough by the teaspoonful on greased cookie sheets, brush with remaining egg and allow to dry. If you are making thumbprints, use your thumb to make an indent in the top of each cookie. Bake in 350° F. for 10-15 minutes. The bottoms of cookies should be slightly browned when done. Top with lemon curd if you made the thumbprints. Watch the video on how to make these bars here: https://www.youtube.com/watch?v=-AeJrnNgK5c.