How to turn line breaks into double line breaks?

I'm trying to turn a plaintext list of items into separate paragraphs. As it stands, without using a tamper plugin, the items have a single line break between them and using the "Convert line breaks into HTML" text filter they at least display with a line break between them. However, we'd like to have paragraphs instead of line breaks. We can achieve this by adding an extra line break between the lines, but so far I've not been able to achieve this using the tamper plugins.

I tried using the "Find replace REGEX" plugin, using the find string "/\n/" and the replacement "\n\n" but that just replaced line breaks with the literal string "\n\n". I then tried escaping the slashes, so using "\\n\\n", but that didn't work either.

Any recommendations? Thank you.