Combine the packet of purple Jell-O and 1 cup of boiling water in a bowl. Whisk until Jell-O is fully dissolved in the boiling water.

In a 2-cup measuring cup, pour in ½ cup - ¾ cup of Malibu rum. Add cold water to the 1 cup measurement line. (Depending on how strong you’d like the jell-o shots, adjust the amount of Malibu and then add water as needed to make 1 cup total of liquid).

Add the rum and the cold water to the grape Jell-O mixture.

Pour the Jell-O mixture to fill an extremely thin layer in the bottom of plastic shot glasses (about 1 teaspoon per layer. Please note: if you are using tapered cups, you will use less liquid in the bottom layers to create the same thickness of layer - so you may be using only ½ teaspoon for the first couple layers and then gradually up to 1 teaspoon for the final layers. Set the shot glasses inside the refrigerator for about 30 minutes to chill and set. (The Jell-O layers set quickly because they are so thin.)

After about 30 minutes, mix together the white layer. We’ll do the ingredients for the white Jell-O ⅓ at a time so that you don’t have to mix it up all at once and manage such a large quantity. The Jell-O will stay liquid at room temp or with a few seconds in the microwave, so you CAN mix it all at once, but we prefer to do ⅓ at a time.

For ⅓ of the total white Jell-O: Sprinkle two packets of clear gelatin over 1 cup of cold water in a heat-proof bowl or measuring cup. Whisk together and set aside for 5 minutes to allow the gelatin to bloom. Place in the microwave for 15 seconds and then whisk to dissolve the gelatin completely. Add 1 cup of cold water and 1 full can (14 oz.) of sweetened, condensed milk. Whisk to fully combine the ingredients. Check that the mixture is room temperature. If it is warm at all, place the white Jell-O mixture into the refrigerator or allow to cool to room temperature.

Add a very thin layer (about ½ teaspoon) of the white Jell-O mixture over the purple layer. Return Jell-O shots to the refrigerator to chill until set (another 15-30 minutes.)

Mix the next layer of Jell-O just as you did with the purple. Dissolve blue Jell-O in 1 cup of boiling water. Mix Malibu and cold water to make an additional 1 cup of liquid and combine with the blue Jell-O. Once cooled to room temperature, add your thin layer of blue Jell-O over the white layer.

Continue adding white layers of Jell-O and colored layers until you finish with the final red layer of Jell-O. As you use up all of the white Jell-O mixture, follow the same process as Step 5 to make another batch. IF you use all of the Jell-O from each color (96 Jell-O shots), you will need about 3 batches of white Jell-O.

Whip heavy cream or use canned whipped cream to top the Jell-O shots JUST BEFORE SERVING. Add a ¾-1” strip of Airheads rainbow candy or top with colorful sprinkles.