As everybody else says,

     $hash{ 'key1' }{ 'key2' }
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takes the contents of $hash{ 'key1' } to be a symbolic reference, and then tries to get the value of that corresponds to 'key2' against a hash with the name = $hash{ 'key1' }

So

     $hash{ 'key1' } = 'foo';
     $hash{ 'key1' }{ 'key2' } = 'bar'; # (2)

     # (2) means find %(current pkg)::foo and do
     $(current pkg)::foo{ 'key2' } = 'bar';
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Still a hash of hashes, but I find this rather tricky to use. You always have to be aware of the fact that $hash{ 'key1' }{ 'key2' } is being evaluated via symbols

However, $hash{ 'key1' }->{ 'key2' } would be used like this:

     my %hash;
     $hash{ 'key1' } = {}; ## ref to hash

     $hash{ 'key1' }->{ 'key2' } = 'foo';

     ## above equivalent to
     my %hash = (
           key1 => {
                  key2 => 'foo'
           }
     );
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And, of course, I wrote up to here and realized that it doesn't really fit to the original problem! sigh.

I probably should have pointed to

       $hash{ 'key1' } = 'foo';
       $hash{ 'key1', 'key2' } = 'bar';
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But I really dislike that notation. ( and the way things gets stored when you do it that way )

As for the original problem, I would have done:

       my %hash = (
             food => {
                   name => 'Apple',
                   color => 'Red'
             }
       );

       my $food = $hash{ 'food' };
       print "$food->{ 'color' } $food->{ 'name' }\n";
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Is this explanation better ? :-)