Telling two bodies to find common angle?

This is for a woodworking project. Is there a way to tell these two bodies to find their common angle? Doing subtract, at least in the way I have tried doesn’t work in the way you would cut the wood panel in real life.

hi @Svanwinkle,
I think the fastest way is to extrude the sides as new bodies then draw the cutting shape on the upper plane of the bodies. When you have the shape, it can be simply cut-extruded on both sides.
Here is a small video about my idea, hope it helps:

That’s great! Pretty straight forward and simple solution, thanks!