Hi kwebber,
Good to hear from you again. I'll be happy to answer your question so you can write a one time cheque.
Since this will be a one time transaction, I recommend creating an expense cheque. You can do this by clicking the Plus (+) icon > Cheque > when filling out the cheque details, you can leave the cheque Payee info blank. You can enter the name of the company or person you're writing the cheque to in the Description field or Memo. I'll attach an image below for reference. Once you've entered the info, you can Print, Save or Close the cheque.