Add brown sugar, cinnamon, flour, walnuts together in a medium bowl.
Using a rubber spatula mix the ingredients together.
Using the rubber spatula mix in the butter.
Sprinkle the topping over the top of the pie.
Place the filled pie on a baking pan.
Bake at 400 degrees for 20 minutes.
Do not remove the pie from the oven but reduce the oven temperature to 375 degrees for another 30-35 minutes.
Remove from the oven. Set aside to cool for 3 full hours.
Using a small pot, heat the heavy whipping cream until simmering
Pour over the chocolate chips in a medium bowl
Whisk until smooth and then let sit for 5 minutes
Spoon the ganache into a piping bag
Cut the tip off and drizzle over the pie
Allow the chocolate to harden before serving!