how to check if specific array key exist in multidimensional array then append that array into new array in PHP? [duplicate]

I have a multidimensional array e.g. (this can be many levels deep) and another array to be appended like this:

$another_array = array();
$array = array(
    [1] => array ()
    [2] => array ()
    [3] => array (
        [4] => array (
            [5] => array (
                [8] => array()
            )
        )
    )
)
);

I am trying to loop through it to see if a certain key exists then array append to another array

$another_array = array(); 
$keysearch = 8;

function findKey($item, $keysearch){
    foreach($array as $key => $item){
        if($key == $keysearch){
            $another_array[] = $array[$key]; // append array to another array
        }else if(is_array($item) && var_dump(findKey($item, $keysearch))==true){
            $another_array[] = $item; // append array to another array
        }
    }
}

Output I want

$another_array = [0] => array (
                [4] => array (
                    [5] => array (
                        [8] => array()
                    )
                )
            )

But it finds nothing and not append it.