To soften ice cream, microwave in carton or glass bowl for 15-20 seconds.
Spoon softened ice cream into pie crust, leaving about 1/4 in around the top. Smooth with spatula or back of spoon dipped in warm water.
Spread half of a container of cool whip over the top of the ice cream.
Drizzle peanut butter sauce over whipped topping. If you do not have peanut butter sauce, you can soften a few teaspoons of smooth peanut butter in the microwave for 10-15 seconds and then use a spoon to drizzle it.
Gently place mini marshmallows over the top of the pie.
Cover with lid or plastic wrap and place in freezer for at least 4 hours or overnight.
Let sit for 15 minutes before cutting. Slice into 6-8 wedges and serve. If you have trouble cutting through it, dip knife in hot water.