Using a mixer or food processor, process the roasted chestnuts with the heavy whipping cream and melted butter until smooth.
Transfer to a mixing bowl and mix in maple syrup, nutmeg, salt, and eggs.
Melt chocolate in the microwave or in a double boiler.
In a small bowl, mix one cup of the pie filling with the melted chocolate.
Pour remaining pie filling into the pie crust.
Top with the chocolate/pie filling mixture.
Bake for 15 minutes.
Reduce oven temperature to 350 F and bake for another 40 minutes or until a toothpick comes out clean.
Cool to room temperature and then refrigerate until ready to enjoy. The pie may be eaten warm or cold. Try it both ways and let me know which way you like better!
Notes
You can use store-bought roasted chestnuts or make them from-scratch. Boulder Locovore has a great guide on roasting chestnuts.
Mix about 2 cups of crushed graham crackers with 6 tablespoons of melted butter and press into a deep dish pie pan.