Angular: Events and "subscribe is not a function" error

I have just started diving into some basic Angular 4 and am stuck listening to an emitted event. Here's a pretty minimal example that reproduces the problem (at least on my end):

DateSenderComponent is "broadcasting" the current date which is then to be processed by its parent AppComponent (see below):

import { Component, Output } from '@angular/core';
import { EventEmitter } from "events";

@Component({
  selector: 'app-date-sender',
  template: '<button (click)="sendDate()">Send</button>'
})

export class DateSenderComponent {
  @Output() dateSent = new EventEmitter();

  sendDate(){
    var dt = new Date();
    console.log(dt);
    this.dateSent.emit(dt.toString());
  }
}

AppComponent is supposed to listen to the broadcasted date event:

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  template: '<app-date-sender (dateSent)="dateReceived($event)"></app-date-sender>'
})

export class AppComponent {
  dateReceived(value){
    console.log('Result: ', value);
  }
}

From various beginners tutorials I figured this is the way to listen to events. However, instead of printing out the received date value, when loading the page I get the following error:

AppComponent.html:1 ERROR TypeError: instance[output.propName].subscribe is not a function

at createDirectiveInstance (core.es5.js:10727)

at createViewNodes (core.es5.js:12086)

at callViewAction (core.es5.js:12530)

at execComponentViewsAction (core.es5.js:12439)

at createViewNodes (core.es5.js:12113)

at createRootView (core.es5.js:11991)

at callWithDebugContext (core.es5.js:13206)

at Object.debugCreateRootView [as createRootView] (core.es5.js:12666)

at ComponentFactory_.create (core.es5.js:9912)

at ComponentFactoryBoundToModule.create (core.es5.js:3448)

Unfortunately, I wasn't able to find any information about what this actually means and I also couldn't figure it out on my own.

One thing that seems to be a hint: When I change the AppComponent template to listen to some event that doesn't get emitted anywhere (for example <app-date-sender (someStringSent)="dateReceived($event)"></app-date-sender>) then the error disappears. So there seems to be a connection between the actual output event and the template listening to it and it seems to be the cause of the problem.

Can anyone point me in the right direction?