We took each one and flattened it a bit (just with the palms of our hands) and cut them out with heart cookie cutters:
After we baked them, I melted some white baking chocolate (in a bowl in the microwave), stirred in a few drops of red into one batch to make pink, a lot of red into another batch to make red, and none into one batch to leave it white. Then we poured the chocolate into decorating bottles (You can find these in the baking section of any craft store; I bought mine at Wal-mart for $1 each!) and the kids used them to decorate the cooled cookies! No mess, easy peasy, and fun for the kideos!
ANOTHER VALENTINE IDEA FOR BOYS!
I previously found the cutest idea for making Valentine cookies with boys: use heart-shaped cookies to make Spiderman cookies. Well I just found another idea from Sugar Swings: chocolate lego men! You can buy lego-men ice or candy molds and use candy melts to make Valentine-colored lego guys, then use them to make cards for your boys to give out!