Here is an example for breadcrumbs schema (thanks for this btw which I found yesterday). The .Params.subtitle is the one with some values with a / which appears as \/.
<script type="application/ld+json">{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":{{ site.BaseURL }},"name":"{{ site.Title }}"}},{"@type":"ListItem","position":2,"item":{"@id"{{ with .Parent }}{{ with .Parent }}{{ .Permalink }}{{ end }}{{ end }},"name":"{{ with .Parent }}{{ with .Parent }}{{ .Title }}{{ end }}{{ end }}"}},{"@type":"ListItem","position":3,"item":{"@id"{{ with .Parent }}{{ .Permalink }}{{ end }},"name":"{{ with .Parent }}{{ .Title }}{{ end }}"}},{"@type":"ListItem","position":4,"item":{"@id":{{ .Permalink }},"name": "{{ .Title }} - {{ .Params.subtitle }}"}}]}</script>