Using mitigating$/$compensating control$($s$)$ to address inadequate segregation of duties

Scenario

Due to limited resources, the Accounting Manager, Andrew Black, at Love Connect Company is responsible for approving vendor invoices for payment and signing the vendor cheques. The General Manager, Debbie Love, is aware of the control deficiency, but states that she will implement temporary mitigating controls until she can afford to hire an individual to approve vendor invoices. Everyone is currently overwhelmed with work and can not take on any additional responsibility.

Question

What type of temporary mitigating control if any, could be implemented to reduce the likelihood of accounting irregularity by the Accounting Manager, Andrew Black.