Cream butter and sugar in a medium mixing bowl; add eggs, one at a time, beating well after each addition. Combine pumpkin, milk, bourbon, salt, ginger, nutmeg, and cinnamon. Add pumpkin mixture to egg mixture, mixing well.
Pour filling into pastry shell. Bake at 450° for 10 minutes. Reduce heat to 325°, and continue baking 45 minutes or until a knife inserted in center comes out clean. Cool before serving.