How to add HTM/EJS support to Express serve-index

Simply put, I cant seem to find more detailed docs on Serve-index, I want to add EJS and HTM support. (server.js)

const express = require('express')
const bodyParser = require('body-parser')
var finalhandler = require('finalhandler')
var http = require('http')
var serveIndex = require('serve-index')
var serveStatic = require('serve-static')
const app = express()
app.use(express.static('src'))
app.use('/src', express.static(__dirname + 'src/'))
app.set('views', './pages')
app.set('view engine', 'ejs')
app.use(bodyParser.urlencoded({ extended : true }))
var index = serveIndex('pages', {'icons': true})
var serve = serveStatic('pages')
var server = http.createServer(function onRequest(req, res){
  var done = finalhandler(req, res)
  serve(req, res, function onNext(err) {
    if (err) return done(err)
    index(req, res, done)
  })
})
server.listen(3000)

How can i go about adding HTM/EJS index support?