Preheat oven to 350 degrees F. Arrange pastry shell in a 9-inch pie pan; flute edges and set aside. In a 1-quart saucepan, combine raisins with enough water just to cover. Heat and simmer until water is all absorbed or evaporated and raisins are plump. Spread raisins over bottom of pie.

Measure pumpkin, sour cream, 3/4 cup sugar, egg yolks, cinnamon, ginger, nutmeg, cloves and salt into large heavy saucepan. Whisk together until combined. Continue whisking, constantly, over medium heat until just warm to the touch. Set aside.

In small mixing bowl, beat egg whites until foamy. Add cream of tartar and beat until soft peaks form. Gradually beat in remaining 1/4 cup sugar. Increase speed to high and beat until peaks are stiff and glossy. Gently fold egg whites into pumpkin mixture. Spoon filling over raisins in pie shell.

Bake at 350 degrees F for 30 minutes. Sprinkle Gingersnap Streusel on top and bake another 10 to 20 minutes or until sharp knife inserted in center comes out clean. Cool and store in refrigerator. Good cold or reheat to serve warm.

Gingersnap Streusel:
In food processor, combine 5 gingersnap cookies, 1 tablespoon granulated sugar and 1/2 tablespoon all-purpose flour; process until fine crumbs. Add 1 tablespoon chilled butter (cut into small pieces); pulse until crumbly. Add 1/4 cup chopped pecans and mix well.