We’re all for the mason jar meal trend: It saves money and makes healthy food look more attractive, and it couldn’t be easier to whip up a quick bite on the morning of a busy day (or the night before).

But before you start jarring everything in sight, use caution (and oven mitts) when baking. After removing full jars from the oven, let them cool completely before screwing on the lid, and then refrigerate them immediately.