Heat oven to 350 F. lightly grease 9 inch pie plate. Beat eggs in large bowl; stir in sugar, butter and vanilla. Stir together flour, cocoa and salt; stir into butter mixture. Stir in chocolate chips and walnuts. Pour into prepared pie plate. Bake 30 minutes or until set. Cool. Serve warm or at room temp. Garnish with whipped cream or serve with ice cream if desired.