Stir in the salted roasted peanuts until every peanut is well coated in the melted white chocolate and the mixture looks thick and evenly mixed.
Using a tablespoon or small cookie scoop, drop mounds of the white chocolate–peanut mixture onto the parchment-lined baking sheet, leaving a little space between each cluster.
While the clusters are still warm and glossy, immediately sprinkle the tops with pastel sprinkles, pressing them very lightly if needed so they stick.
Let the clusters sit at room temperature until fully set and firm, about 1–2 hours, or place the baking sheet in the refrigerator for 20–30 minutes to speed things up.
Once set, gently peel the clusters off the parchment and transfer them to an airtight container, separating layers with parchment paper if stacking. Store at cool room temperature for up to 1 week, or refrigerate if your kitchen is warm.
