1. Prepare the Filling Mixture:

• Ensure your Cool Whip is fully thawed in the refrigerator.
• Crush about 3/4 of the bag of M&M’s candies. You can place them in a sturdy Ziploc bag and gently crush them with a rolling pin or mallet, leaving some small pieces for texture. Reserve the remaining whole and crushed M&M’s for decoration.
• In a medium bowl, whisk together the hot fudge sauce and 1 cup of the thawed Cool Whip until blended.
• Add the dry instant chocolate pudding mix to the bowl. Stir well with a spoon or spatula for about 2 minutes until thoroughly combined and slightly thickened.
• Gently stir in the crushed M&M’s. Set this filling mixture aside briefly.

2. Assemble First Layer on Foil:

• Tear off a long piece of aluminum foil (at least 24 inches). Lay it flat on your counter or a movable tray/cutting board (that will fit in your freezer).
• Arrange 4 ice cream sandwiches side-by-side (touching) on the center of the foil to form the base layer (likely forming a square or rectangle).

3. Add Filling and Repeat Layers:

• Carefully spread half of the prepared Cool Whip/fudge/pudding/M&M mixture evenly over the first layer of ice cream sandwiches.
• Arrange another 4 ice cream sandwiches on top of the filling mixture, directly aligning with the bottom layer.
• Spread the remaining half of the Cool Whip/fudge/pudding/M&M mixture evenly over the second layer of ice cream sandwiches.
• Place the final 4 ice cream sandwiches on top, again aligning with the layers below. You should now have three layers of sandwiches and two layers of filling.

4. Frost and Decorate:

• Gently frost the top and sides of the stacked ice cream sandwiches with the remaining thawed Cool Whip from the tub. Use a spatula for a smooth or swirled finish.
• Sprinkle some of the reserved crushed M&M’s over the top.
• Press the remaining reserved whole M&M’s decoratively into the top and sides of the Cool Whip frosting.

5. Freeze Thoroughly:

• Loosely wrap the entire ice cream sandwich cake with the aluminum foil it was built on (or carefully cover with additional foil/plastic wrap).
• Place the wrapped cake carefully into the freezer on a flat surface.
• Freeze for at least 4 hours, or preferably overnight, until completely firm.

6. Final Garnish and Serve:

• When ready to serve, unwrap the frozen cake.
• If desired, drizzle the top with chocolate sauce and add sprinkles for extra festivity.
• Slice the frozen cake into portions using a large, sharp knife (running the knife under hot water briefly can help make cleaner cuts).
• Serve immediately.