Thanks @rdwatters this works like a Boss! I am using it in my META tag to specify the author of the site / page.
@Dave_Taht I noticed that the author META is specified , but empty on your website’s blog posts.
Ex: On your latest post:
<meta name="description" content="Comparing theoretical results with reality for fq-codel, the next generation">
<meta name="author" content="">
The following code, adapted from @rdwatters’ answer, works for me. (There might be a shorter syntax).
<meta property="author" content="{{if .Params.author}}{{.Params.author}}{{else}}{{ .Site.Params.author }}{{end}}" />