Be sure to work fast when layering the ingredients. I like to start with putting some of the mix-ins and some of the fudge ripple in the bottom of the chilled container – marshmallows, fudge, and crumbled crackers or cookies – then add a layer with just-churned custard, then more of all three ingredients, continuing until everything is used up. Avoid stirring because you want the chocolate ripple to remain distinct. Just layer ’em all up, and when you scoop, you’ll have big, moist pockets of dark chocolate and marshmallow. If you don’t have a blowtorch, you can broil the marshmallows on a baking sheet in the oven. Watch them carefully and turn them over as they brown.