Open the peaches and pineapple, reserving 1/2 cup of the peach juice. Drain both fruits thoroughly - excess liquid will make the salad watery. Chop the peach slices into bite-sized pieces, about 1/2 inch chunks. Spread the fruit on paper towels for 5 minutes to remove more moisture.

In a dry skillet over medium heat, toast the chopped pecans for 3-4 minutes until fragrant and slightly darker, stirring frequently. Remove immediately to a plate to cool. Burnt nuts turn bitter fast, so watch closely.

In a large bowl, beat the cold heavy cream with an electric mixer on medium-high speed until stiff peaks form, about 3-4 minutes. The cream should hold its shape when you lift the beaters. Do not overbeat or it will become grainy.

Sprinkle the dry pudding mix over the whipped cream. Add the reserved 1/2 cup peach juice. Gently fold together with a rubber spatula until no streaks of pudding powder remain and the mixture is smooth and thick, about 1 minute.

Add the chopped peaches, drained pineapple, mini marshmallows, toasted pecans, and cottage cheese (if using) to the cream base. Fold gently until everything is evenly coated. The mixture will look loose at first - it firms up as it chills.

Cover the bowl tightly with plastic wrap and refrigerate for at least 2 hours, preferably overnight. The pudding mix thickens the cream and the marshmallows soften slightly, creating that signature fluffy texture. Stir once before serving.