Preheat the oven to 350 degrees F.
For the filling, using an electric hand mixer, combine the potatoes, 1 cup of the sugar, the butter, eggs, vanilla, salt, and spices. Mix thoroughly. Add the milk and continue to mix. Pour the filling into the pie crust and bake for 35 to 45 minutes, or until a knife inserted in the center comes out clean. Place the pie on a rack and cool to room temperature before covering with meringue.
For the meringue, using an electric mixer, beat the egg whites until soft peaks form; beat in the remaining 1/4 cup sugar 1 tablespoon at a time. Continue beating until the sugar dissolves and the mixture is glossy and stiff, but not dry. With a rubber spatula, spoon the meringue onto the pie, forming peaks. Make sure the meringue touches the crust all around. Sprinkle with a pinch of granulated sugar. Bake for 10 to 12 minutes, or until delicately browned. Cool and serve.