Line an 8x8 or 9x9 pan with parchment paper.

Add the peanut butter chips to a medium mixing bowl. Place the chocolate chips in a separate medium mixing bowl.

One at a time, microwave each bowl for 2 minutes, pausing every 30 seconds to stir the chips so they don’t overcook. Once the chocolate is creamy, without lumps, when stirred, you’re ready for the next step.

Remove the lids and foil from both frostings. One at a time, microwave them for 1 minute.
Pour the white frosting into the bowl with the melted peanut butter chips and pour the chocolate frosting into the bowl with the melted chocolate chips.

Stir each bowl vigorously until fully mixed. Both flavors should still be in their own bowls at this point.

Alternate pouring each flavor into the prepared pan. This gives it that swirled look.

Tap the pan on the counter before placing it in the fridge for 4 hours or until fully set.

Remove from the fridge and slice into 1-inch pieces.