I call it the Filmflash transition and its not ready made in Premiere. I do not know for FCP.
You will have to make it your self.
First clip add the Fast Blur effect and the Levels effect.
10 frames from the end set keyframes for bluriness, RGB white input and RGB gamma.
5 frames from the end set RGB Gamma to 50.
Now go to the last frame and set RGB white input to 0 and bluriness to 20.
For the second clip place same effects and set keyframes in reverse.
(first frame bluriness 20, RGB white input 0 etc.)
When ready you can make a Preset out of the effects.