Note: This game is also titled Cooking Guide: Can't Decide What To Eat? and Shaberu! DS Oryouri Navi.
Use the "Timer" function on any of the recipes that require time to be tracked. After the timer has completed and the recipe has finished, you will unlock the "Chef" mini-game from Game And Watch, with both the Game A and Game B variations. Alternately, on a recipe that uses the built-in timer, use it, and intentionally allow the time to run out before completing the recipe.
Cook twenty recipes to unlock the "History And Staff" option at the "Settings" menu. Select that option to view the game's credits on the touch screen and a summary of your cooking on the top screen.
Successfully complete the indicated tasks to unlock the corresponding recipe:
Play the game on your birthday to get a birthday message as well as a birthday icon on the top screen.
Play the game on January 1.