Put poison in the cookies and cookie monster won't need any more than the first batch, and save yourself a lot of work as it will take 6,000,000 batches at 15 minutes a batch. 15 minutes divides into an hour 4 times so you can make 4 batches an hour. So divide 6,000,000 batches by 4 batches an hour which equals 1,500,000 hours which if you divide by that by 24 hours in a day equals 62,500 days If you divide 62,500 by 365 days a year excluding leap years will take you 171.233 years. You should be finished cooking by the year 2191 around February as long as you don't fall asleep or have too many heart attacks during those years. As I said it would be easier to poison the Cookie monster with poison cookies in the first batch. He's had a good long life.