To prepare the raspberry sauce, combine first 4 ingredients in a medium, heavy saucepan; stir well with a whisk. Bring to a boil over medium heat, stirring frequently. Cook 2 minutes. Stir in raspberries; cook 4 minutes, stirring gently. Remove from heat. Stir in 1 tablespoon liqueur. Pour sauce into a bowl; cover and chill 1 hour.
Preheat oven to 300°.
To prepare torte, combine chocolate and 2 tablespoons liqueur in a small, heavy saucepan; cook over low heat until chocolate melts and mixture is smooth, stirring occasionally with a whisk. Place butter and 1/2 cup sugar in a medium bowl; beat with a mixer at medium speed 1 minute or until fluffy. Add egg; beat 1 minute. Gradually add milk; beat at low speed (mixture will look curdled). Add chocolate mixture, cocoa, and 2 tablespoons cornstarch; beat at low speed until combined.
Place the egg whites, cream of tartar, and salt in a medium bowl; beat with a mixer at high speed until soft peaks form using clean, dry beaters. Gradually add 1/4 cup sugar, 1 tablespoon at a time, beating until stiff peaks form. Gently fold one-fourth of egg white mixture into chocolate mixture; gently fold in remaining egg white mixture. Spoon chocolate mixture into an 8-inch springform pan coated with cooking spray. Bake at 300° for 45 minutes or until a wooden pick inserted in center comes out almost clean; run a knife around outside edge. (The torte falls as it cools.) Cool on a wire rack.
Note: Grand Marnier adds a wonderful depth of flavor to his indulgent-tasting dessert. But if you must go alcohol-free, substitute water or orange juice.