Begin by laying a single layer of ice cream sandwiches in a 9x13-inch dish, placing them side by side with no gaps.

Next, take your softened ice cream and spread a generous layer about 1 inch thick over the layer of ice cream sandwiches.

Sprinkle a generous handful of M&M's over the ice cream layer, ensuring they are evenly distributed.

Carefully place another layer of ice cream sandwiches on top of the M&M's, then add another layer of softened ice cream and repeat with M&M's until desired height is reached.

Cover the assembled cake tightly with plastic wrap and place in the freezer for 4 to 6 hours to set completely.

After chilling, let the cake sit at room temperature for about 5 to 10 minutes before slicing into squares.