We have done these...they are great. You don't leave the oven on...you just heat it up..and then turn it off and let the oven sit overnight.

ONE word of caution...we found that with small children it was much better to break up several of the steps over several days...it takes a long time otherwise to do all the Bible reading and preparation and they lose interest before you are done...but if you do the nut step one night....etc it goes much quicker on the night you actually put them in the oven. Also...even doing each step off and on during the day works well if you have the time...but don't try to do it all at once with children under the age of about 6....

Did I miss it? How long do you cook the cookies at 300? Do you actually cook them all night?