1. Grease five (eight-inch) aluminum pans or three (eight- or eight- and- a- half-inch) springform pans.
2. Prepare the fruit purees. Process each fruit in a blender or food processor until completely smooth. Measure to ensure you have about one and a half cups puree. Keep refrigerated until ready to use.
3. In a medium saucepan, combine sugar and water over medium-high heat. Insert a candy thermometer. Let boil until mixture reaches 240 degrees Fahrenheit. If the temperature passes 240 degrees, it’s okay, but if it reaches 250 degrees, which is sugar’s hardball stage, you will have to throw out the sugar and start over.
4. Meanwhile, in the bowl of an electric mixer, whip egg whites until soft peaks form.
5. When sugar mixture reaches 240 degrees Fahrenheit, remove from heat and very slowly drip into the whipped egg whites, while mixing at high speed. (If you pour in the hot sugar mixture too fast, it will kill the egg whites and you’ll be left with meringue soup.) When you are done pouring in the sugar, set a kitchen timer to seven minutes and continue whipping at high speed.
6. After seven minutes, whisk together the meringue with one of the fruit purees. Pour into pan and freeze until firm. Repeat with each layer.
7. When ready to assemble, layer each layer on top of another, alternating colors which have the best contrast. Return to the freezer.
If you do need to get rid of a batch of sugar, do it right away. Although it will be very hot, if you wait until it cools it will get hard. Pour it onto a piece of aluminum foil and let cool before tossing.