Use .html instead of .html.twig

source/blog.html

@@ -0,0 +1,14 @@
+---
+layout: default
+title: Blog
+body_class: page--blog
+use:
+  - posts
+---
+<h1>Blog</h1>
+
+<ul>
+  {% for post in data.posts %}
+  <li><a href="{{ post.url }}">{{ post.title }}</a></li>
+  {% endfor %}
+</ul>