This Craft CMS plugin will let you recursively nest blocks in your matrix fields.

Has a relatively light touch so it'll work on existing matrix fields, and won't break or destroy your content in the event the plugin is removed.

That said, this plugin comes with a warning. It is built on undocumented API's and relies on many front-end hacks for it to function. That means there is always the risk it could break on future Craft CMS updates. Use at your own risk.

A common use case is to use group blocks to generate a grid layout of content.

When editing Matrix fields, you'll be presented with a new option when creating and editing block types. Ticking this checkbox will set the block type as a "group" type. Along with whatever fields you assign to this block type, you will also now be able to nest blocks within it.

The plugin comes with it's own custom Twig tag, which works the same way as Craft's {% nav %} tag:

<ul>
	{% matrixgroup block in entry.matrixField %}
		<li>
			{{ block.type.name }}
			{% ifchildren %}
				<ul>
					{% children %}
				</ul>
			{% endifchildren %}
		</li>
	{% endmatrixgroup %}
</ul>

You can also accomplish this in a non-recursive manner:

<ul>
	{% for block in craft.matrixGroup.topLevel(entry.matrixField) %}
		<li>
			{{ block.type.name }}
			{% set children = craft.matrixGroup.children(block) %}
			{% if children|length > 0 %}
				{# ... #}
			{% endif %}
		</li>
	{% endfor %}
</ul>

Refer to Craft's documentation of {% nav %}, as they are essentially identical in usage and function. Just replace nav with matrixgroup and you're good to go!

• Allowed child block types setting on group block types
• Min-depth and max-depth settings for each block type
• Depth limit setting on group block types