gistfile1.php

<?php
/**
 * Creates nested date archive list for a specific category
 *
 * @since 1.0.0
 */
function ja_category_archive_list() {

	global $post;

	$posts = get_posts( 'posts_per_page=-1&cat=154' );
	$year  = '';
	$month = '';

	echo '<ul class="date-archive-list">';

	foreach( $posts as $post ) {

		setup_postdata( $post );

		if ( ucfirst( get_the_time( 'F' ) ) != $month && $month != '' ){
			echo '</ul></li>';
		}
		if ( get_the_time( 'Y' ) != $year && $year != '' ){
			echo '</ul></li>';
		}
		if ( get_the_time( 'Y' ) != $year ){
			$year = get_the_time('Y');
			echo '<li><h2>' . $year . '</h2><ul class="monthly-archives">';
		}
		if ( ucfirst( get_the_time( 'F' ) ) != $month ){
			$month = ucfirst( get_the_time( 'F' ) );
			echo '<li><h6>' . $month . '</h6><ul>';
		}

		echo '<li>';
			echo '<span class="date">' . get_the_time( 'jS' ) . '</span> - ';
			echo '<a href="' . get_permalink() . '">' . get_the_title() . '</a>';
		echo '</li>';
	}

	echo '</ul>';

	wp_reset_postdata();
	wp_reset_query();           
}
add_action( 'genesis_entry_content', 'ja_category_archive_list' );