Macadamia Nut Cream Pie

1/2 cup granulated sugar
4 tablespoons sifted cornstarch
1/2 teaspoon salt
2 cups milk
4 egg yolks, lightly beaten
1 tablespoon butter
2 tablespoons Kahl?a liqueur
3/4 cup chopped macadamia nuts
2 cups whipped cream
1 (9-inch) baked pie shell

Combine sugar, cornstarch and salt in top of a double boiler. Slowly add milk, stirring constantly. Place over gently boiling water and cook 10-15 minutes, stirring constantly until mixture thickens to a loose custard.

Blend 1/2 cup of the hot sugar mixture into the egg yolks, 1 tablespoon at a time. Slowly pour and beat the warm egg mixture back into the remaining sugar mixture. Continue cooking 3 to 5 minutes, until the custard is thick. Add butter; cool to room temperature.

Stir in the Kahl?a and all but 1 tablespoon of the nuts. Fold in 1 cup whipped cream. Fill pie shell, garnish with remaining whipped cream and reserved nuts. Chill.