01 -  In a chilled mixing bowl, beat heavy cream with powdered sugar and vanilla extract using an electric mixer or whisk until stiff peaks form. Set aside. 
 02 -  Add a layer of assorted cake cubes to the bottom of each jar, then spoon a layer of pudding over the cake. 
 03 -  Add a layer of mixed berries and banana slices, followed by a generous dollop of whipped cream. 
 04 -  Sprinkle chocolate chips or candy pieces over the whipped cream layer, if using. 
 05 -  Repeat the sequence of layers until the jars are filled. Finish with whipped cream and scatter rainbow sprinkles on top. 
 06 -  Serve immediately, or refrigerate jars for up to 4 hours to achieve ideal texture before serving.