I've been making these cookies for decades and they fool people -- they don't taste or have a texture of an oatmeal cookie. They come out thin, chewy and buttery, not dry and chunky like most oatmeal cookies.
Preheat oven to 350 degrees. With electric mixer, cream shortening, butter and sugar together until smooth. Add egg, milk and vanilla to the mixture and blend until smooth and silky.
Gradually add flour into the bowl with sugar mixture. Sprinkle soda and salt and mix thoroughly. Add oatmeal and mix slowly until incorporated into batter. Fold in cranberries (Craisins) -- you can also substitute raisins, or chocolate chips, or nuts, or whatever strikes your fancy.
Drop by spoonfuls onto ungreased cookie sheet. Bake for 10 to 12 minutes until browned on edges and top. Cool for 2 minutes before removing to a cooling rack. Enjoy!!