Attaching Interrupt to internal Brownout detection

[Edie00773]

Hello all,
I'm using an ESP32-WROOM-32UE for a project, and want to fire an interrupt to save a value to flash when the device dteects brownout.
I ahve added a large capacitor to slowdown the brownout and eestimate I should have about 500ms from detection to the device failing.
Howevr, I can't find anywhere what code I need to stop the built in interrupt that resets the chip, and replace it with my own intterupt.
many thanks
Edward