Add semi-sweet chocolate chips (¼ cup), caramel chips (½ cup), and butter (2 tablespoons) to a medium microwave-safe bowl. Microwave on 50% power (important!) for 1 minute. Stir, then microwave in 30 second increments at 50% power until melted (mine takes about 2 minutes total). Mix until mostly smooth (it's okay to have a few lumps).
Once melted & smooth, add marshmallows (2 cups) - do not stir them in. Microwave for 1 minute.
Mix chocolate mixture until smooth (it's okay if a few of the marshmallows aren't fully melted), then stir in rice krispy cereal (2 cups). Mix until coated and let cool for a few minutes.
Once mixture is warm to the touch (i.e. not too hot to touch) scoop mixture in ¼ cup scoops, spray hands with nonstick cooking spray, roll into a ball, and then flatten into discs (don't press together too firmly or your cookies may get too hard). Place on parchment to harden.
If desired, you can also press mixture into a loaf pan and make them into bars.
