In a large, microwave-safe bowl, heat 2 cups of water in the microwave until boiling, about 4-5 minutes. Stir in the apricot gelatin until dissolved, then add the marshmallows and stir until those are melted.

Drain the apricots, reserving the juice, and chop them into bite-size pieces. Drain the pineapple, discarding the juice (unless you plan to make the cooked pineapple topping mentioned in the notes section below). Slice the bananas.

Add the reserved apricot juice and enough cold water or apricot nectar to make 2 cups to the jello mixture. Add the chopped apricots, crushed pineapple, and sliced bananas. Transfer to a 9x13 pan and refrigerate for 4 hours until set.

Beat the heavy cream, powdered sugar, and vanilla extract using a mixer until stiff peaks form. Spread over the chilled jello before serving.