Milk chocolate squares or chocolate shavings for garnishoptional
Stir the mini chocolate chips into the chocolate pudding; set aside.
Beat the chilled heavy whipping cream at medium speed until soft peaks begin to appear. Sprinkle the powdered sugar and vanilla extract over the whipped cream and beat at medium-high speed until stiff peaks form (but do not overbeat or you will end up with butter). Gently fold 1 cup mini marshmallows into the whipped cream; set aside.
Set out eight half-pint Mason jars (or 8-ounce glasses). Place about 2 tablespoons chocolate pudding into the bottom of each jar (which will use up half of the total pudding). Coarsely crush three graham crackers in a plastic baggie using a rolling pin or the flat side of a meat mallet; divide the crumbs between the eight jars, sprinkling to make an even layer over the pudding. Use a knife to divide the marshmallow whipped cream in half. Place a dollop of the whipped cream into each jar, spreading it to cover the graham cracker crumbs and using up half of the total whipped cream.
Crush 3 more graham crackers and divide the crumbs between the jars, sprinkling them on top of the whipped cream. Place 2 more tablespoons of chocolate pudding on top of the crumbs in each jar, using up the remainder of the chocolate pudding. Crush the final 3 graham crackers and divide the crumbs between the jars, sprinkling them on top of the pudding. Divide the remaining marshmallow whipped cream between the jars, spreading it to cover the crumbs.
Screw the lids on the jars (or tightly cover the tops of the glasses with plastic wrap) and refrigerate for at least an hour and up to overnight.
Just before serving, line a baking sheet with aluminum foil and lightly spray with nonstick cooking spray. Divide the remaining 1 ½ cups marshmallows into 8 little piles, each with a circumference similar to the size of your jars/glasses. Broil the marshmallows until toasted to your liking, watching the entire time. Allow the marshmallows to set for about 10 minutes, then use a spatula to transfer each "mound" to the top of each trifle. If desired, top each trifle with a milk chocolate square or some chocolate shavings. Serve immediately.
Instead of broiling mounds of marshmallows in the oven, you may sprinkle them over the tops of the trifles and then toast them with a kitchen torch. You may choose to toast them before refrigerating to save time, but they won't be warm and melty after chilling. You may also leave them untoasted, if you wish.