my %h2 = (
	'AAA' => 'aaa',
	'BBB' => 'bbb',
	'CCC' => {
		'A1' => 'a1',
		'B1' => 'b1',
		'C1' => {
			'A2' => 'a2',
			'B2' => 'b2',
			'C2' => 'c2END',
		},
	},
	'DDD' => 'ddd',
);

sub ddump
{
	my $ref = shift;
	my $deep = shift||1;
	for my $k ( sort keys %$ref )
	{
		if ( ref $ref->{$k} )
		{
			print "\t" x $deep."$k =>\n";
			ddump( $ref->{$k}, $deep+1 );
		}
		else
		{
			print "\t" x ($deep)."$k => $ref->{$k}\n";
		}
	}
}

ddump( \%h2 );


##</code><code>##


use CGI qw /:all -nph/; #on Win32
$|++;

	sub nest
	{
		my $it = shift;
		ref $it ? complex_table($it) : $it
	}

sub complex_table
{
	my $hr = shift;
	# could test here to ensure that $hr is indeed a hash ref.
	table( { -border => 2, -bordercolor => 'green', -cellspacing => '0', },
		map Tr( td( {-valign=>'top'}, $_ ), td( nest( $hr->{$_} ))), sort keys %$hr
	);
}

my %h1 = (); # feed your HoH here

print
	start_html,
	complex_table( \%h1 ),
	end_html;