Line sheet pan with parchment paper.
Pour yogurt into prepared sheet pan and spread out evenly.
Drizzle melted chocolate over yogurt and use toothpick or knife to swirl it into yogurt.
Sprinkle with dried cranberries and pistachios.
Freeze for 3+ hours to set.
Cut and serve immediately. Freeze any leftovers right away and don’t let it sit out at room temperature.