Add the mixed nuts and white chocolate chips to your slow cooker. Set it to low heat and let everything melt together for about 1 hour, stirring occasionally to ensure even melting and prevent scorching. The chocolate should be smooth and fully melted when ready.
While the chocolate is melting, line a baking sheet or tray with parchment paper. This will make cleanup easier and prevent the candy from sticking as it sets. Also, have a cookie scoop or spoon ready for portioning the clusters.
Once the chocolate has fully melted, give it a good stir to coat the nuts evenly. Working quickly, fold in ¾ cup of the Easter M&Ms, stirring just enough to distribute them without overmixing (the candy coating can start melting if stirred too much). Immediately use a cookie scoop or spoon to drop small portions of the mixture onto the prepared tray. Speed is key here - the chocolate will start firming up as it cools.
Before the candy sets, press a few extra M&Ms on top of each cluster for color and crunch. Sprinkle generously with Easter sprinkles to add a festive touch.
Transfer the tray to the refrigerator and chill for about 30 minutes or until the chocolate is completely firm. Once set, the clusters are ready to enjoy! Store them in an airtight container at room temperature or in the fridge for a longer shelf life.