1. Create a Non-inventory Item for Purchase by navigating to Lists > Accounting > Items > New
-- Click For Purchase
-- Enter name in Item Name/Number field and populate other required fields.
-- Select an appropriate Expense Account that posts against sales
2. Create check by navigating to Transactions > Bank > Write Checks
-- Select the Customer the check being issued to
-- Select the item from step 1 under the Items tab
Note: The above helps track the expenses and also link check under the customer record