Reading a value out of a query

Hi there,

I am currently building a custom print format. So far it works very well but I am struggling with one aspect:
I build a print format for time sheet that queries the account_manager of the company behind the project.
So far, so good. However, by default it prints the e-mail address of the account_manager, but I want to get the full name (probably first_name + last_name). Any suggestions?

So far this brings me to the e-mail address, but not the name:
{{frappe.db.get_value(“Customer”, doc.customer, “account_manager”)}}

Thanks so much!