External HTML in Components?

I’m having a difficult time figuring out how to do something along the lines of

<custom-component>
  <h1>Custom HTML Here</h1>
  <p>More custom stuff inside my component.</p>
</custom-component>

It seems like a simple enough task, but I’m unable to find anything that describes how I would go about doing this. Can Aurelia 1 even do such a thing, or should I be using a different solution? Maybe something with <router-view> (seems unnecessarily complex, plus there’s bonus complexity for interactions with our current router setup)?