I tried that but the @inner array gets cleared within the if statement and the reference now points to an empty array. However, having messed with this most of the afternoon, I came up with this that seems to work.

Making $inner a ref to an array and de-referencing for the push seems to solve the problem.

my @outer = ();
my $inner = []; 
my $n = 0;
while (<DATA>) {
    chomp;
    push @$inner, { DATA => $_ };
    if ($n == 1) {
        push @outer, { INNER => $inner };
        $inner = [];
        $n = 0;
    } else { $n++; }
}
[download]