Can NGINX work as Webserver and Proxy Server At Same Time?

We have a situation where we need to serve the login page from server_A (NGINX), get the user authenticated from here and once authenticated route the request ta a page which resides in a different server i.e. Server_B. All subsequent requests will come to Server_A and it will first check the user and session validity and then route to Server_B. This way the session and security is maintained by server A and rest of the work is done by server B.

My question here is that can we acheive this from NGINX server ?