Sending Cookie From Express API Back To Ember

My problem concerns the user of Passport with Express API and returning a cookie back to Ember.

I have sent the Username and password to the Express server and Serialized this to get an ID. I can see the identification using:

console.log('Serializing User: ', req.session.passport.user)

OUTPUT: Serializing User: 59957ccd9da3da8d1dce2a72

I can get access to this identification but I am struggling to send it back to Ember as a cookie.

So far I have:

Express

  app.post('/api/authenticate',
    passport.authenticate('local'),
    function(req, res){
      console.log('User ID: ', req.session.passport.user)

      //Write the cookie
      res.cookie('CookieName', req.session.passport.user)

      //Get the cookie as a cookie and stringify
      var cookie = JSON.stringify(res.req.headers.cookie)
      res.send({'name': 'CookieName', 'value': cookie})
  })

Ember

 authenticate(username, password){
    console.log(username);
    console.log(password);
    console.log(apiHost)

//Send a promise to express with username and password to be resolved
///get express to search database
  var promise = this.get('ajax').request(apiHost, {
    method: 'POST',
    data: {
      username: username,
      password: password
    }
  })
  //accept data as a cookie

  return promise.then((result) => {
    //debugging
    var obj = result;
    console.log(obj);
    var message
    if(result.error){
      console.log("error exists - let's reject")
      message = promise["error"];
      return Promise.reject(message);
    } else {
      console.log("promise accepted")
      message = promise;
      return Promise.resolve(message);
    }
  })
  }

Postman Pretty states: Unexpected 'B' Postman Raw states: Bad Request

This is my first time using Passport, Cookies and putting in place Authentication.

I just need to accept the JSON and have it become a cookie so that I can request access to the session in Express in the future

Thanks in advance!