app/themes/hugo-theme-stack/layouts/partials/widget/toc.html

{{ if (.Context.Scratch.Get "TOCEnabled") }}
    <section class="widget archives">
        <div class="widget-icon">
            {{ partial "helper/icon" "hash" }}
        </div>
        <h2 class="widget-title section-title">{{ T "article.tableOfContents" }}</h2>
        
        <div class="widget--toc">
            {{ .Context.TableOfContents }}
        </div>
    </section>
{{ end }}