Pie : Preheat oven to 350 degrees, racks in the middle.
Puree 1 1/2 cups of the toasted hazelnuts in a food processor until they turn into a hazelnut paste, past the 'crumble' stage. Set aside. Chop the remaining 1/2 cup of hazelnuts and set aside seperately, these will be sprinkled on top after the pie is baked.
To make the pumpkin pie filling, whisk together the brown sugar, pumpkin pie spice blend, salt, and arrowroot. Stir in the pumpkin puree, and vanilla. Now stir in the eggs and coconut milk until just combined. Set aside.
Before filling the pie crust, crumble the hazelnut paste on top of the pie dough into the pie plate, quickly and gently press it into a thin layer across the bottom creating a layer of hazlenuts that will sit between the dough and the filling. Using the last egg gently brush the decorative edges of the pie dough. Use a fork to prick the pie dough a few times to prevent air bubbles. Fill the pie crust with the filling and bake for about 50 minutes - the center of the pie should just barely jiggle when you move the pie - the edges should be set.
Let the pie cool a bit, this makes slicing less messy. Serve straight or with a dollop of bourbon-spiked, sweetenend whipped cream or creme fraiche, and a sprinkling of chopped hazelnuts.
Kathy's Pumpkin Pie Spice Blend:.
Use a coffee grinder to separately grind each of the following: cinnamon, allspice, and cloves. Smash the cinnamon a bit before grinding it. The spices should be powder-fine, and sifted into a bowl together. Stir in the ground ginger, and use in any recipe calling for a pumpkin pie spice blend.