As we approach the limits of CMOS scaling, researchers are developing "beyond-CMOS" technologies to sustain the technological benefits associated with device scaling. Spin-tronic technologies have emerged as a promising beyond-CMOS technology due to their inherent benefits over CMOS such as high integration density, low leakage power, radiation hardness, and non-volatility. These benefits make spintronic devices an attractive successor to CMOS - especially for memory circuits. However, spintronic devices generally suffer from slower switching speeds and higher write energy, which limits their usability. In an effort to close the energy-delay gap between CMOS and spintronics, device concepts such as CoMET (Composite-Input Magnetoelectric-base Logic Technology) have been introduced, which collectively leverage material phenomena such as the spin-Hall effect and the magnetoelectric effect to enable fast, energy efficient device operation. In this work, we propose a non-volatile flip-flop (NVFF) based on CoMET technology that is capable of achieving up to two orders of magnitude less write energy than CMOS. This low write energy (≈2 aJ) makes our CoMET NVFF especially attractive to architectures that require frequent backup operations - e.g., for energy harvesting non-volatile processors.