It's not actually a single report but you can easily grab a total of sales receipts and purchase payments then calculate the difference for a cash based profit figure.
First go to Sale >> View payments, then open the advanced search box and set the preset date range to match your accounting period.
In the top right you'll get a total figure for all sales receipts:
The same concept works on the purchase side too by going to Purchases >> View payments.
This method works on the basis that you're tagging all your income and expenditure to invoices (which usually is the case). If you tag items directly from the bank and post directly to a nominal code from there this won't get picked up. Also journals would need to be factored in too.