Modify User Profile Widget's Gravatar Size in Genesis Child Theme

functions.php

<?php
/**
 *
 * Modify the size of the Gravatar in the User Profile Widget
 *
 * @author Calvin Koepke
 * @since 1.0.0
*/
add_filter( 'genesis_gravatar_sizes', 'ck_user_profile' );
function ck_user_profile( $sizes ) {
	$sizes['Extra Large Image'] = 340;
	return $sizes;
}