Squirt tube frosting in the center of 16 of the cookies. Sprinkle with colored sugar to coat the frosting; shake off excess. Set aside.
In a small microwave-safe bowl microwave the caramels and the cream on 100 percent power (high) for 1 to 1-1/2 minutes, stirring every 30 seconds until melted and smooth.
Spread about 2 teaspoons of the caramel mixture on the bottoms of the undecorated cookies (let stand if caramel mixture is too thin). Top with decorated cookies. Store in the refrigerator. Makes 16 sandwich cookies.