[GNC] How do I enter a transaction with an account not in the Gnucash ledger?

[Mark Phillips]

How do I enter the following transaction in gnucash?

I have a business checking account and a personal checking account. My
Gnucash file only tracks the business checking account. Occasionally, I
grab the wrong debit card from my wallet to pay for a business expense.

For example, let's say I use my personal debit card to pay $100 of business
expenses. For this example let's say I bought $100 of nuts and bolts (since
I feel like a nut not being able to work this out). How do I enter this
transaction into my business Gnucash ledger to account for (1) transferring
money out of my business checking to reimburse my personal checking and (2)
record the expense in the appropriate business account?

Thanks!

Mark

PS The good news is I have only done this twice since 2015!