WordPress: How to show all posts in a category on the sidebar

Goosebumps Episodes

On the right where it shows goosebumps episodes, it only shows the 10 most recent posts in the "Goosebumps Episodes" category.

Does anyone know how I can make it show all of the posts in the category instead?

I am not using any plugins. Here is the code that displays the recent posts on the sidebar:

<h2>Goosebumps Episodes</h2>

<ul>

<?php

foreach ($recentposts as $post) {

if ($post->post_title == '')

$post->post_title = sprintf(__('Post #%s'), $post->ID);

echo "<li><a href='".get_permalink($post->ID)."'>";

the_title();

echo '</a></li>';

}

?>

</ul>

PHP:

Any help would be appreciated.