Lightly spray a 10-cup Bundt pan with cooking spray. (Original recipe called for a 6 cup Bundt pan, but I used a larger size, just to be safe.)

For the grape layer: Add 3/4 cup boiling water to grape gelatin mix in a medium bowl; stir 2 minutes until completely dissolved. Refrigerate for 20 minutes to cool. Whisk in 1/2 cup sour cream. Skim off as many bubbles as you are able to before pouring into a Bundt pan. Skim off any remaining bubbles, especially around the outside edges of the pan. Refrigerate 30 minutes until thickened but not set.

For the lemon layer: Meanwhile, add 1 1/2 cups boiling water to lemon gelatin mix; stir 2 minutes until completely dissolved. Chill 25 minutes to cool. Whisk in 1 cup sour cream. Skim off any bubbles the same way as directed previously. Gently spoon or pour over the grape layer in the mold. Chill 30 minutes, until thickened but not set.

For the lime layer: Add 1 1/2 cups boiling water to lime gelatin mix; stir 2 minutes, until completely dissolved. Chill 25 minutes. Whisk in 1 cup sour cream. Skim off any bubbles the same way as directed previously. Gently spoon or pour over lemon layer in mold. Refrigerate 6 hours, until firm.

When ready to serve, fill your sink halfway with hot water. Set the Bundt pan in the water for about 5 seconds and remove. Put your serving plate upside down over the top of the Bundt pan. Clamp it tightly over the pan with both hands and flip. The Jell-O mold should release from the pan and be right side up on your serving dish. Cut into slices and serve.