1. Preheat the oven to 350 degrees F. Chop 1/2 cup pecans, combine with cinnamon together in a small bowl, set aside.
2. Whisk pumpkin, sour cream, sugar, salt, eggs, egg yolk, allspice and nutmeg together in a medium bowl.
3. Sprinkle pecan and cinnamon mixture onto the pie shell. Pour the filling on top of the nuts and place the pie in the center of the oven to bake. Bake until the top browns lightly and pie is set 55 to 60 minutes. Pie will be fairly solid when gently shaken by the edges of the pie tin. Top with the remaining pecans.