title: Vercel Serverless functions send response cookie
body: <p>I want to send an 'httpOnly' cookie with my response from Vercel serverless functions. I am NOT using Express.</p>
  
  <p>I tried <code>res.setHeader("Set-Cookie", `ck=${cookie_value}`);</code></p>
  
  <p>This doesn't work. How do I send cookies and put an expiry time on it?</p>