See: https://make.wordpress.org/community/2018/10/10/converting-wordcamp-shortcodes-to-gutenberg-blocks/#comment-26002

session.html

<div id="session-1" class="session session-1 track-1" style="grid-column: track-1; grid-row: time-0800 / time-0900;">
	<h3 class="session_title">Talk Title</h3>
	<span class="session_time">
		<span class="session_time_start">8:00</span>
		<span class="session_time_sep"> - </span>
		<span class="session_time_end">9:00</span>
	</span>
	<span class="session_track">Track: 1</span>
	<span class="session_author"><span class="session_author_gravatar"><img src="..."></span>Mike Rofone</span>
</div>