Once all the balls are rolled, place the baking sheet in the fridge for at least 20–30 minutes (or 10–15 minutes in the freezer). Chilling helps them hold their shape when you dip them in chocolate.
When the peanut butter balls are almost done chilling, add the chocolate chips to a microwave-safe bowl. Microwave in 20–30 second bursts, stirring after each round, until the chocolate is completely melted and smooth. (Alternatively, melt the chocolate in a heatproof bowl set over a pot of gently simmering water.)
Remove a few peanut butter balls from the fridge at a time and dip them into the melted chocolate, using a fork to lift them out and gently tap off the excess chocolate on the side of the bowl.
Place the coated balls back onto the parchment-lined sheet. Repeat with the remaining balls, reheating the chocolate briefly if it starts to thicken.
Once all the balls are coated, return the tray to the fridge for about 20 minutes, or until the chocolate is fully set.
Store the chocolate peanut butter balls in an airtight container in the fridge for up to 1 week, or in the freezer for up to 2 months. Let them sit at room temperature for a few minutes before eating if frozen.
For a crunchier version, you can swap in crunchy peanut butter or stir in a small handful of crushed pretzels or crisp rice cereal before rolling the balls (this technically adds another ingredient, but it’s a fun twist when you have a few extra minutes). If you prefer things less sweet, use dark chocolate chips instead of semi-sweet, or reduce the powdered sugar slightly and accept a softer, more truffle-like texture. For a little flair, drizzle the tops with a bit of extra melted chocolate in a contrasting type (white chocolate over dark looks pretty) or sprinkle with a tiny pinch of flaky sea salt before the chocolate sets. To make these more portable for busy workdays, roll them slightly smaller so they’re true bite-size and freeze a batch—then you can toss a few into a small container in the morning and they’ll be perfectly chilled by afternoon snack time. If you need them nut-free, you can experiment with sunflower seed butter in place of peanut butter, just know you may need to adjust the powdered sugar to get a rollable consistency.