Lilly only wants certain items, so if you don't have them prepared they won't appear as an option. Also of note, when making food in your cookbook you have to make sure you have all the ingredients purchased in order to actually prepare the recipe. "Perpare" should appear under the selected food item if you have all the stuff needed to make it. I'm going to look into adding some kind of notification to make it more apparent when you don't have all the required items to make a dish.