Hi, loubega,
some people cook peas, others don't - frozen ones most typically fed are, with any luck, a bit mushy, which works for my fish, anyway.
Personally, I try squashing them in my fingers and nip off tiny, bite-sized bits with a thumbnail and flick them into the water - or try, as after a few tanks, the pea bits tend to start sticking to the hands, and I get a fair bit on the ceiling, lol.
(I HATE pea-feed day, having hand problems - but my bettas and some of the other fish love it, so it balances out VERY heavily weighted on the good side.)
Several bits about the size of your betta's eye would be good.
And the bits I put in tend to sink, athough they don't tend to get very far down before being snapped up, lol.
Whole peas tend to be too big for a betta to eat, and while some apparently manage, I don't see how...
I believe most of us feed peas weekly, to help clean their systems out, as well as because they're a favorite food of many bettas.
Freeze-dried shrimp would probably be relished, although, as you likely know, too many dried foods can cause bunged-up bettas, so frozen shrimp, bloodworms and other such delicacies are more often fed.
But the more variety fed, within reason, the better.
