Creating Rainbow Jello Cubes involves layering various flavors of Jello, which can be a fun process. Follow these step-by-step instructions for success:

1. Prepare the Pan: Lightly grease a 9×13-inch baking dish with nonstick spray or oil. This will help in removing the Jello cubes later.

2. First Layer: In a bowl, dissolve the first flavor of Jello in 1 cup of boiling water. Stir until completely dissolved. Then, add 1 cup of cold water. Pour this mixture into the prepared pan and refrigerate for about 30-60 minutes, or until set.

3. Second Layer: For the second layer, repeat the same process with a different flavor of Jello. Once the first layer is firm, prepare the second flavor and pour it gently over the first layer. Again, refrigerate until set.

4. Continue Layering: Continue this process for all six flavors. If you want to add a creamy layer, mix one packet of unflavored gelatin with sweetened condensed milk in between layers as desired.

5. Final Chill: After all layers are set, allow the Jello to chill in the refrigerator for at least 2 hours or overnight for the best results.

6. Cutting the Cubes: Once completely set, remove the Jello from the pan. Use a sharp knife to cut it into small cubes.

7. Serve: Transfer the cubes to a serving platter or individual cups for a beautiful presentation.

These steps will help you create a stunning treat that everyone will enjoy!