In a large bowl, whisk together the gluten-free 1:1 baking flour, 1 teaspoon sugar, and salt. Cut 8 tablespoons of cold butter into small pieces and add to the flour mixture. Use a pastry blender or your fingertips to cut the butter into the flour until it resembles coarse crumbs with some pea-sized pieces of butter remaining.

In a small bowl, whisk together 3 tablespoons ice water, 1 1/2 tablespoons sour cream, and 1 1/2 teaspoons white vinegar. Gradually add the liquid mixture to the flour mixture, a tablespoon at a time, mixing until the dough just comes together. Form the dough into a disc, wrap in plastic, and refrigerate for at least 30 minutes.

On a lightly floured surface (using gluten-free flour), roll out the chilled dough into a 12-inch circle. Carefully transfer the dough to a 9-inch pie plate. Trim and crimp the edges as desired. Refrigerate the pie crust while you prepare the filling.

Preheat oven to 375°F (190°C). For the filling: In a large bowl, whisk together 2/3 cup sugar, 1 teaspoon cinnamon, and 1/2 teaspoon ginger. Add 15 ounces pumpkin puree, 2 large eggs, and 1 cup heavy cream. Whisk until smooth and well combined.

Pour the pumpkin filling into the chilled pie crust. Bake for 50-60 minutes, or until the edges of the filling are set but the center still jiggles slightly. If the crust starts to brown too quickly, cover the edges with foil.

Remove the pie from the oven and let it cool completely on a wire rack for at least 2-3 hours before slicing and serving. The pie will continue to set as it cools.