Step 1

Melt the marshmallows and heavy cream. Place 3 cups mini marshmallows, 1/2 cup of the heavy cream, and 1/4 teaspoon kosher salt in a large microwave-safe bowl. Microwave on HIGH in 30-second bursts, stirring between each, until the marshmallows are fully melted, about 2 minutes total. (Alternatively, melt in a small saucepan over low heat.)

Step 2

Add the chocolate. Set aside about 2 tablespoons semi-sweet chocolate chips from a 12-ounce bag for garnish. Immediately add the remaining chocolate to the warm marshmallow mixture. Stir until the chocolate is melted and the mixture is smooth.

Step 3

Cool the chocolate mixture. Set the chocolate-marshmallow mixture aside to cool until barely warm to the touch, about 30 minutes.

Step 4

Whip the cream to stiff peaks. Place the remaining 2 cups cold heavy cream and 2 tablespoons granulated sugar in the bowl of a stand mixer fitted with the whisk attachment. (Alternatively, use an electric hand mixer or whisk and a large bowl.) Begin beating on low speed, gradually increase the speed to medium-high, and beat until stiff peaks form, 1 to 2 minutes.

Step 5

Reserve 1 cup of the whipped cream and fold in the remaining cream. Reserve and refrigerate about 1 cup of the whipped cream for topping the pie. Fold the remaining whipped cream into the cooled chocolate mixture until no streaks of cream remain.

Step 6

Transfer the filling to the pie crust. Transfer the filling into a baked pastry crust or crumb crust and smooth into an even layer.

Step 7

Garnish and chill the pie. Refrigerate until the filling firms up, at least 1 hour and up to 3 hours. Top with the reserved whipped cream and chocolate chips.

Step 8

Serve. Cut into slices and serve.