How do I neatly splice plywood for a desk?

[seerikand]

Hello,
I'm in the middle of building a desk in my daughter's room. The idea is to utilize an inner corner where I put "strips" on both walls of the inner corner. This way, the tabletop rests against the strips towards the wall.

There will also be wall-mounted cabinets that the board will rest on instead of table legs. I hope you understand somewhat, but it's an extremely simple solution.

Now to the question;
In the actual inner corner, two sheets of construction plywood will meet/join. How do you do this in the best/most aesthetically pleasing way?

Cutting each end at 45 degrees seems difficult considering the boards are about 50cm wide. That is, it doesn’t take much margin for error for the gap to grow. I prefer "straight surfaces" against each other. See image.

 

[Kane]

I probably had the biscuit with them.
But shouldn't you have björkplyfa instead?

 

[Skogsmusen]

I did it like this.

What I used was the overhand router, glue in the joints, and then they are clamped together on the underside with these.