Onsie cookies from i heart baking are the perfect treat to serve at a baby shower. The cookie's creator, Michele, uses a simple sugar cookie recipe from Pretty Party Cakes and bought a onesie cookie cutter to cut out the shapes. She uses royal icing to decorate them. These cookies are easily customizable with the colors and you can also include the babies initials. Onesie cookies are an adorable favor, just wrap them up in a cellophane bag with some colorful ribbon.