1Heat oven to 325°F. In large bowl, beat 3/4 cup butter and 1/3 cup sugar with electric mixer on medium speed 1 minute. Stir in cocoa and flour until mixture is crumbly. Press firmly and evenly against bottom and side of 9 1/2-inch deep-dish glass pie plate or 10-inch regular glass pie plate. Sprinkle with chopped nuts. Bake 20 to 25 minutes or until edge appears dry. Cool completely, about 45 minutes.
2In 2-quart saucepan, melt 1/4 cup butter and the chocolate over low heat, stirring occasionally; remove from heat. In small bowl, mix 1 cup sugar and the cornstarch with wire whisk; stir into chocolate mixture.
3In small bowl, beat eggs with electric mixer on medium speed about 5 minutes or until thick and lemon colored; stir into chocolate mixture. Cook chocolate mixture over medium heat 5 minutes, stirring constantly, until thick and glossy. Stir in vanilla. Cool 10 minutes, stirring occasionally.
4In medium bowl, beat whipping cream with electric mixer on high speed until stiff. Fold chocolate mixture into whipped cream. Pour over crust. Cover; freeze about 4 hours or until firm. Remove from freezer; let stand 30 minutes before cutting. Top with whipped cream; sprinkle with almonds. Store covered in freezer.