In the comments, you can use
`\`` to escape a (code formatted) backtick, like so:
resulting in
However, in question (and answer) posts, it doesn't work. It ends up looking like three backticks: ```.
To get what you want you have to use <code>...</.code>, or least that is how I worked around the issue:
<code>`</code> which gives: `


`` ` ``. But in comment Markdown this results in `` ` ``.