This is opuntia linguiformis, or cow's tongue opuntia. The fruit are red fleshed and are usually pretty good.
Burbanks only ever developed one opuntia for fruit production, all the others were intended as cattle fodder. There are much better fruiting opuntia out there than burbank's spineless types. I do have the one he developed as a fruit crop, it's probably the rarest thing I own, and it is not spineless. It has long spines, but no glochids. It is some kind of Robusta hybrid. The reds have been better than any other colour I've tried, including yellow, and the flavour is different. Reds have a raspberry-like flavour, whereas the yellows/ oranges are kind of melony.