In a bowl of a standing mixer place sugars, cinnamon, allspice and nutmeg and mix well. Add eggs one at a time then pumpkin and sour cream and blend until well incorporated.
On a floured surface roll out the bottom disk of pie crust and place in pie pan. Fix edges to fit around the edges, fold any extra dough and flute the sides. Add pumpkin mixture and spread evenly. Bake at 425 degrees for about 15 minutes, then reduce heat and cook for about 40 minutes at 350 degrees.
Apply an egg wash on edges of crust that is 1 egg whisked with about a tsp of milk. Using a pastry brush, brush edges. this will help give a golden crispy crust.
A metal pie ring sprayed with non-stick cooking spray will help cook the pie and keep the edges from burning. If using, carefully remove from the pie for the last ten minutes of cooking.