Step 1

Preheat the oven to 425 degrees F (220 degrees C).

Step 2

In a large bowl, mix together the pumpkin, sweetened condensed milk, and egg yolks. Stir in 1 teaspoon cinnamon, ginger, nutmeg, and salt. In a large glass or metal bowl, whip egg whites until soft peaks form. Gently fold into pumpkin mixture. Pour filling into pie shell.

Step 3

Bake for 15 minutes in the preheated oven. While the pie is baking, prepare the streusel topping: In a small bowl, combine the flour, brown sugar, and 1 teaspoon cinnamon. Blend in the cold butter with a fork or pastry blender until the mixture is crumbly. Mix in the chopped nuts. Sprinkle the topping over the pie.

Step 4

Reduce the heat to 350 degrees F (175 degrees C). Bake an additional 40 minutes, or until set.