Creme de Cacao Pie

1 envelope unflavored gelatine
1/2 cup cold milk
1/4 cup butter or margarine
2/3 cup granulated sugar, divided
6 tablespoons Hershey's cocoa
3 eggs, separated (at room temperature)
1/4 cup creme de cacao (chocolate-flavored liqueur)
1 (9-inch) baked pastry shell

In a small bowl, sprinkle gelatine over milk; let stand 5 minutes to soften.

In medium saucepan, over low heat, melt butter; remove from heat. Stir in 1/3 cup sugar and cocoa. Add gelatine mixture; blend well.

Slightly beat egg yolks; stir into chocolate mixture. Over medium heat, cook, stirring constantly, until mixture is hot and gelatine is dissolved. Do not boil. Remove from heat; stir in creme de cacao. Cool to room temperature, stirring occasionally.

In large mixer bowl, beat egg whites until soft peaks form; gradually add remaining 1/3 cup sugar, beating until stiff peaks form. Fold in chocolate mixture; pour into pie shell. Cover; refrigerate until set, about 4 hours.

Refrigerate leftovers.