You may want to group your print statements; and you don't need to concatenate strings and variables (like "<title>".$Title."</title>") - you can print them together in one double-quoted string ("<title>$Title</title>").

Consider:

foreach $Title (keys %{$HASH}) {
   my $abstract  = shift @{$HASH->{$Title}};
   my $procedure = pop @{$HASH->{$Title}};
   print $OUT "<title>$Title</title>\n",
              "<abstract>$abstract</abstract>\n",
              (map { "<recipe>$_</recipe>\n" }@{$HASH->{$Title}}),
              "<procedure>$procedure</procedure>\n";
}
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