Fudge Bottomed Chocolate Layer Pie

This is very rich, but very good! It is always requested to bring for Thanksgiving.

1 c. hershey's special dark chocolate chips, divided
6 tbsp. milk, divided
1 (6 oz.) packaged chocolate crumb crust
1 1/2 c. miniature marshmallows
1 (8 oz.) whipped topping, thawed and divided

Place 1/3 cup chocolate chips and 2 tbsp. milk in microwave safe bowl. Microwave 30 seconds on high; stir. If necessary, microwave an additional 15 seconds at a time, stirring after each heating, until chips are melted and mixture is smooth when stirred. Spread on bottom of crust. Refrigerate while preparing the next step.
Place marshmallows, remaining 2/3 cup chocolate chips and remaining 1/4 cup milk in small saucepan. Cook over medium heat, stirring constantly, until marshmallows are melted and mixture is well blended. Transfer to separate large bowl; cool completely.
Stir 2 cups whipped topping into cooled chocolate mixture; spread 2 cups mixture over chocolate in crust. Blend remaining whipped topping and remaining chocolate mixture; spread over surface of pie.
Cover; freeze several hours or until firm. Garnish as desired. Cover; freeze remaining pie.