I have done hundreds of them.
Cut so the teeth cut into the plastic laminate. Cross cut with a circular saw and sharp blade. I usually tip the saw up and over the corner to cut the back splash, but if you decide to use some other tool be sure the teeth cut into the plastic. A jig saw or a pull saw, but not a traditional hand saw.
If one end goes against the wall, cut that end. Then you can hide a sloppy cut with a end splash.
Also, if you need to scribe it to fit the end wall, a belt sander is your friend. Same thing along the back wall. Caulk (Cabinet maker in a tube) is also your friend. Be sure to sand into the plastic. Rasps will work too, but those electrons really help.