that one looks like it was done on the table saw. On edge to cut the angled part and then flat to define the vertical section.
I've also seen them done in two pieces. Cut the angled piece and leave a flat in the middle then come back and apply a long square piece for the stand off. Seems like there would be less waste that way
I'm voting it was table saw. If I were making this, I'd cut the miters on a square piece of stock and add the square part to save material. glue and dominoes, or simply glue and nail depending on needed strength.
Looks like a 15° raised panel bit to me. The Amana Tool 54117 15° raised panel router bit looks like a possible candidate. Just don't try to do it all in one pass and keep the router speed down to 12,000 RPM.