use HTML::Parser;
use HTML::Entities;

my $html = '<div align="center">Your "HTML" page goes here</div>';
my $enc = '';

my $p = HTML::Parser->new(
  unbroken_text => 1,
  default_h => [ sub { $enc .= join('', @_) }, "text" ],
  text_h => [ sub { $enc .= HTML::Entities::encode_entities($_[0]) }, "text" ],
);
$p->parse($html);
print $encoded;