Unable to sent cookies to a endpoint from a variable

[DarylStark]

I'm trying to sent a cookie to a endpoint that I received in a previous call.

For example; I first send a request to my login endpoint

let login = POST http://localhost:5000/login

{
    "username": "user1",
    "password": "xxx"
}

The response contains a cookie in the headers with the session

Set-Cookie    0: session=very_long_session_id; HttpOnly; Path=/

Next, I want to send this cookie to other endpoints;

GET http://localhost:5000/endpoint
Cookie: $login.headers.Set-Cookie[0]

But the RESTbook send the literal string $login.headers.Set-Cookie[0] instead of the value that was in the first cookie. When I drop the [0] index of the variable, it sends the complete string, including the ['s and "'s. It should send the cookie from the request.