I have done meal expensives several ways over the years and it pretty much comes out the same. I have done a sample menu and costed it out based on my grocery receipts. I have also just added up everything we spent on groceries for the year and then you factor in how many are daycare meals and how many are family meals and get a percentage. A lot depends on the type of meals you serve too. If you are opening cans of stuff then it is easy to cost out. If lunch is last night's leftovers then you have to know how much it cost to make last night's supper and then to take a percentage of that. I just used excel to record the grocery slips and then added the column at the end.