Ours are bigger. I'm more wondering how much to cut them.

Usually deco end panels don't get cut - can you post a picture of what yours look like? They are usually designed to look like a door on end. Otherwise they are more of a wainscot panel in which case it would go to the wall.

They are 3/4" deeper than the cabinets (16" panel to 15" cabinet including the door) and my thought was that they'd need to be scribed because we had to shim the cabinets. The wall isn't plumb. What would be helpful to include in the picture?

I think the picture of the panel and the wall area you are talking about... It still seems odd...

Tosca, am I remembering right that you are doing IKEA but cutting the uppers down to be shallower than the standard?

Is your side panel flat (like an actual cover panel) or decorative, like a door front? And how high up is the backsplash going... all the way, or stopping partway up the uppers?

Hi Hillside, the kitchen is Ikea and we're not cutting down our uppers, but we are stacking them. we've had to do significant shimming in order to get them passably plumb and level.

I think we will need to cut the panel because as it is it would sit proud of the doors, whereas I want it to be flush with the doors. I was supposed to be under the impression that it needed to sit firmly against the wall and therefore we need to be scribed.

Here is the situation in pictures:

So that looks like a flat panel used to create a gable end detail. The door face will be even with the end of the panel. I would put the door on the cabinet THEN get proper measurement so bumpers etc are included. Then cut back ( scribe to wall )