gistfile1.html

<div class="container">
  <div class="main-content">
    <div class="tc-panel promo-report is-collapsed">
      <div class="tc-panel-header mod-promo-report">
        <div class="tc-panel-header-info">
          <h1 class="tc-panel-header-title mod-promo-report"><span class="icon-starter-report"></span> CERCA Starter Report</h1>
        </div>
        <div class="tc-panel-header-actions">
            <div class="tc-panel-header-actions-item mod-minimize">
              <a class="tc-btn mod-minimize" href="">Expand</a>
            </div><!-- // tc-panel-header-actions-item -->
        </div>
      </div>
    </div><!-- // tc-panel -->
    <div class="tc-panel promo-report">
      <div class="tc-panel-header mod-promo-report">
        <div class="tc-panel-header-info">
          <h1 class="tc-panel-header-title mod-promo-report"><span class="icon-starter-report"></span> CERCA Starter Report</h1>
        </div>
        <div class="tc-panel-header-actions">
            <div class="tc-panel-header-actions-item mod-minimize">
              <a class="tc-btn mod-minimize" href="">Minimize</a>
            </div><!-- // tc-panel-header-actions-item -->
        </div>
      </div>
      <div class="tc-panel-content">
        <div class="promo-report-content">
          <h3 class="promo-report-headline">Leveling Your Students</h3>
          <p class="promo-report-summary">Analyze data to help place your students at a reading level that will challenge them appropriately.</p>
        </div>
        <div class="promo-report-actions">
          <a class="tc-btn mod-primary mod-block" href="">See your data</a>
        </div>
      </div>
    </div><!-- // tc-panel -->
  </div>
  <div class="side-content">
    <div class="assignment-panel"></div>
  </div>
</div>

Just looking at it I would keep the tc-panel out of the descendents, since components should be standalone and not know anything about anything else, even including the tc-panel-content, and -header, etc.
For example you could have tc-header instead, and then mod it to be smaller, or whatever you need to change about it from a typical header?
If tc-panel-header-actions-item is, for example, something that does a float:right, and action items are always on the righthand side it might make sense to just factor that part out into it's own component.