Worktop joint expertise please...

Hi.

I have fitted a U shaped kitchen with a return on one side of the open end (so more 90% of a rectangle really).

I intend to fit 40mm square edged beech worktops using butt joints.

I have a few questions to be honest but my first one is -

Am I best using the dog bone shaped cut outs on the underside with the long bolts or is there another way.?

If this is the best way, do I need to hire a jig or can I just rout elongated T shapes in matching positions 20mm deep?

Thanks

Jim