Add the granulated sugar, lemon juice, vanilla (if using), and a pinch of salt to the cream cheese. Beat until the mixture is smooth and the sugar is mostly dissolved.
In a separate chilled bowl, whip the cold heavy cream with an electric mixer on medium-high speed until it forms soft to medium peaks. Do not overbeat; it should be thick and hold its shape but still look silky.
Gently fold the whipped cream into the cream cheese mixture with a spatula. Take your time so you don’t deflate the cream; you want a light, fluffy base.
Make sure all the fruits are well drained so they don’t water down the salad. Pat them dry with paper towels if they seem extra juicy.
Fold the crushed pineapple, strawberries or raspberries, mandarin oranges, and maraschino cherries into the creamy mixture until evenly distributed.
Slice the bananas just before adding so they stay fresh-looking. Gently fold in the banana slices and chopped pecans, being careful not to mash the fruit.
Pour the mixture into the prepared 9×13-inch dish, spreading it out into an even layer and smoothing the top with a spatula.
Cover the dish tightly with plastic wrap or foil and place it in the freezer. Freeze for at least 6 hours, or overnight, until firm enough to cut into squares.
Before serving, remove the dish from the freezer and let it sit at room temperature for 10–15 minutes to soften slightly. Cut into squares and serve cold, straight from the pan.
Return any leftovers to the freezer, covered well. They will keep their best texture for about 1–2 weeks.
If your nana used different fruits, you can easily adjust this to match your memories. Swap the strawberries or raspberries for chopped peaches or mixed berries, or add a handful of seedless grapes cut in half. For a slightly tangier salad, replace half of the heavy cream with thawed whipped topping or fold in 1/2 cup of sour cream along with the cream cheese. If you remember it sweeter, increase the sugar to 3/4 cup; if you like it less sweet, drop it to 1/3 cup. Toasting the pecans in a dry skillet for a few minutes before chopping will deepen their flavor, or use walnuts if that’s what you have. To keep the bananas from browning even longer, toss the slices in an extra teaspoon of lemon juice before folding them in. For a pretty holiday look, sprinkle a few extra chopped pecans and halved maraschino cherries over the top before freezing. If you prefer individual servings, spoon the mixture into muffin cups lined with paper liners, freeze, then pop them out and store in a container for grab-and-go treats.