What is described is a system and method for offline cementing of a casing hanger and a casing placed in a wellbore of a well. The system includes an isolation sleeve/cementing spool that is configured for engaging the casing hanger, where the isolation sleeve has at least one access port in fluid communication with an annulus formed by the casing in the wellbore. A dummy hanger is housed within the isolation sleeve and is configured for coupling with the casing hanger and is further in fluid communication with the casing. A valve is configured for coupling to the isolation sleeve and is configured to be in fluid communication with the dummy hanger. A quick connector is coupled to the valve and enables quick coupling of a cementing head.