I have resolved - this is the process I am following in case anyone is interested.
During initial registration, user enters a login and password. Both are hashed, sent over HTTPS to the server.
Server DB saves the client login hash and the output to password_hash($pass,PASSWORD_BCRYPT, ["cost"=>12]) to the db.
Later, during login process, user enters login and password. Both are hashed, sent over HTTPS to the server.
Client requests server to search DB for the loginhash, retrieves the password_hash output.
if password_verify($clientpass, $dbpass) return true, then password is valid, else false/password invalid.
This works for me.
Why do I hash the user and the password on the client even though they go over the wire as https? Because fixed lengths are faster to search for in the DB (I mysql prepare all my queries to ensure not to depend on dirty client data). Also because even though the data goes encrypted, I prefer a long sequence of characters over the wire as opposed to a short sequence which a username/password might contain - in my world, it feels better though I believe from what I read I don't get if anything extra for the effort.