Line a baking sheet with parchment paper. Set aside.
In a large microwave-safe bowl, melt the white candy melts in 30-second increments until smooth, whisking in-between intervals.
Repeat in two separate bowls with the red candy melts and in another separate bowl with the blue candy melts.
Pour the melted white chocolate over the parchment paper and spread out with an icing knife so the chocolate is about ¼" - ½: thick.
Immediately dollop blobs of the melted red chocolate and melted blue chocolate in any pattern you like on top of the white chocolate (see photos for ideas). Use a toothpick to spread out the red and blue over the white chocolate.
Immediately sprinkle the M & Ms, then mini marshmallows, then sprinkles over the top. Be sure to do this quickly so the chocolate does not start to harden yet.
Place the baking sheet in the refrigerator to cool for about 10-15 minutes, or until the chocolate has hardened. Break into pieces and serve.
Notes
Makes approximately 8 servingsStore in an airtight container in the refrigerator for up to one week.