One of the truths that I have always held to be self-evident was that to make whipped cream you had to start with whipping cream. Something to do with fats, proteins and binding air into the dairy molecules … you know, science.

But it turns out that evaporated milk, because, well, much of the water has been evaporated out of it, has a high enough percentage of protein to be whip-able, despite having considerably less fat than whipping cream. Good to know, if you’re avoiding fat. Doesn’t taste the same, but that’s what sugar is for.

Anyway, I owe this revelation to Marilyn Kunishi, who wrote asking for help finding a recipe for a frozen dessert — Lilikoi Crunch — that her mother used to make. “The crust was made with cornflake crumbs and it was frozen in an ice cube tray. My mother made it often but I have not been able to find it in her recipe collection. I would love to make it again.”

I searched and failed, then tried my standard trick for solving passion fruit mysteries: substitute lemon for the lilikoi. I asked Google to come up with something within the parameters of lemon, crunch and cornflakes. Up popped a few recipes for Lemon Crunch desserts using cornflakes and frozen in ice cube trays. Bingo.

Kunishi and I picked one and tested it. Neither of us had fresh lilikoi so we made it with lemon, which is easily switchable. The two are equally tart.

The first line of the instructions, however, said to whip a cup of evaporated milk “until stiff,” and I thought, “That’s not going to work.” But upon consulting the website of Carnation (maker of evaporated milk), I found that if you chill the milk and the beaters very well you can indeed do this thing.

Anyway, this very simple recipe turned out light, tart and tasty. You could make it with any kind of fruit juice, just go easy on the sugar if you’re using something sweeter than lemon or lilikoi.

When we compared notes later, I found that Kunishi crushed her cornflakes very fine and used them to make a crust at the bottom and on top of the lemony filling (I crushed mine lightly, just for a topping). The recipe can be used either way.

“The result was just what I remember my mom making, apart from the fact that I used lemon,” Kunishi wrote. “My family enjoyed this trip down memory lane.”

FROZEN LEMON CRUNCH WITH CORNFLAKES

• 1 cup evaporated milk
• 1/3 cup lemon juice (or substitute another fruit such as passion fruit)
• 2 eggs
• 1/2 cup sugar (use less for sweeter fruit juices)
• 1/4 teaspoon salt
• 1 tablespoon grated lemon zest
• >> Topping:
• 1/2 cup crushed cornflakes
• 2 tablespoons sugar
• 2 tablespoons melted butter

Pour milk into mixing bowl. Place bowl and beaters for an electric mixer in freezer 30 minutes or until ice crystals begin to form.

Beat milk with cold beaters about 1 minute, until foamy. Add lemon juice and whip again until fluffy like whipped cream, 1-2 more minutes.

In a separate bowl beat eggs, sugar and salt until well combined and thickened. Stir in lemon zest. Fold mixture into whipped milk, stirring until no streaks remain.

Pour into ice cube trays or loaf pan.

To make topping: Mix cornflakes with sugar and butter. Sprinkle over lemon mixture.

Freeze until firm. Serves 4.

Nutritional information unavailable.

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