<?php
$myArray = 
    Array ( '0' => 
            Array ( '0' => 
                    Array ( 
                           'Date' => '1776-08-08',
                           'Color' => 'Yellow',
                           'Description' => 'Rotten'
                            ) ) ,

            '1' => Array ( ),
            '2' => 
            Array ('0' =>
                   Array ( 
                          'Date' => '2018-05-13',
                          'Color' => 'Red', 
                          'Status' => 'Fresh' 
                           ) ,
                   '1' => 
                   Array ( 
                          'Date' => '1991-03-29',
                          'Color' => 'Green', 
                          'Status' => 'Fresh'  ) ) );

$newArray = array();
foreach ($myArray as $el) {
    $temp = array();
    array_walk_recursive($el, function($v, $k) use (&$temp) {
            if ($k == "Date") {
                $temp[] = $v;
            }
        });
    $newArray[] = $temp;

}
print_r($newArray);