Similar to the cupcake machine pastry bag, you initiate cooking s'mores by clicking on either the sign or tray. From here, you can choose how you want to cook the s'mores and what serving size you want!
Mod for rotational playstyle: When you have two teenagers who are either significant others or promised to each other, they will now be able to do some romance interactions when one of them ages up to young adult. Note: The kissing and make out animations are a little off (see picture), so there are addon packages to disable these for your teen-young adult couples.