$re = '/<h3 class="lined-header">Dagens meny<\/h3><h4>(.*?)<\/h4><p> ?(.*?)<\/p><h4>(.*?)<\/h4><p> ?(.*?)<\/p><a class="link-button" href="\\\\\[\[https:\/\/www\.\\\\\]\(https:\/\/www.fontanhuset.se\/veckan\)website\.com\/weeklymenu">Veckans\]\(https:\/\/www\.\]\(https:\/\/www\.fontanhuset\.se\/veckan\)website\.com\/weeklymenu">Veckans\) meny<\/a>/m';
$str = '<h3 class="lined-header">Dagens meny</h3><h4>Lunch</h4><p> Rotmos elr potatismos med korv</p><h4>Veg</h4><p> Rotmos elr potatismos med vegkorv</p><a class="link-button" href="\\[[https://www.\\](https://www.fontanhuset.se/veckan)website.com/weeklymenu">Veckans](https://www.](https://www.fontanhuset.se/veckan)website.com/weeklymenu">Veckans) meny</a>';
$subst = "$1: $2$3: $4";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php