Python

#recursion

def even_num(n: list) -> list:
    curr = [n[0]]
    succ = n[1:]
    is_even = (curr[0] % 2 == 0)
    is_current_element = (len(n) == 1)

    if is_current_element:
        if is_even:
            return curr
        else:
            return []
    
    return even_num(curr) + even_num(succ)

assert even_num([3,2,4,5,8,6,12,11]) == [2, 4, 8, 6, 12]