PHP匹配大多数外部括号

I have a string that looks like this:

$sample = <<<EOD
lots of gibberish
before what I want{{Template
| x = 1
| y = 2|z= 3}}more gibberish
here too. {{Other|test}}
EOD;

I'd like to get rid of the gibberish and just get:

$sample = <<<EOD
{{Template
| x = 1
| y = 2|z= 3}}
EOD;

I'd normally look for "{{Template" and end with "}}", but my problem is, it might look like this sometimes:

$sample2 = <<<EOD
lots of gibberish
before what I want{{Template
| x = 1
| y = {{Convert|1|2}}|z= {{Convert|3|4}}}}more gibberish
here too. {{Other|test}}
EOD;

In this situation, it opens and closes some curley brackets, but I want it to match this:

$sample2 = <<<EOD
{{Template
| x = 1
| y = {{Convert|1|2}}|z= {{Convert|3|4}}}}
EOD;

How could I do this?

\{(.*)\}/s

That should match the outermost brackets, including newlines in between.

(\{\{Template(.*)\}\})\w+/s

This will match the {{Template start with a }} followed by some gibberish. The "template" part will be stored in $1

\{\{Template[^\{]*(?:\{\{[^\}]*\}\}[^\{]*)*?[^\{]*\}\}

See the demo here

Explain

\{\{Template                //Starts with {{Template
[^\{]*                      //Any chars except {
(?:\{\{[^\}]*\}\}[^\{]*)*?  //Any inner groups+trailing chars conditional
[^\}]*                      //Any chars except {
\}\}                        //Ends with }}