Line a baking sheet with parchment paper to prevent sticking.
Melt the semi-sweet chocolate morsels in the microwave using 30-second intervals, stirring between each until smooth. Pour the melted chocolate onto the prepared tray and spread it evenly. Let it harden completely, refrigerating if needed to speed up the process.
Melt the white chocolate morsels the same way, then pour it over the hardened semi-sweet chocolate, spreading it evenly. Allow this layer to fully set before moving on.
Melt the red, white, and blue candy melts separately. Drizzle each color over the white chocolate layer using a spoon or piping bag. Before they harden, swirl the colors gently with a toothpick to create a marbled effect.
While the candy melts are still soft, sprinkle red, white, and blue star sprinkles along with M&Ms on top so they stick.
Allow the entire tray to harden completely, either at room temperature or in the refrigerator for faster results.
Once fully set, lift the chocolate bark from the tray using the parchment paper edges. Break it into pieces by hand.
Your festive chocolate bark is ready to enjoy!
Notes
Store leftovers in an airtight container at room temperature or in the fridge.