In a medium saucepan melt margarine or butter and unsweetened chocolate over low heat. Remove from heat. Stir in the 2 cups sugar, the 4 eggs, and the 1 teaspoon vanilla. Beat lightly by hand just until combined. Stir in flour.
Spread batter in a lightly greased 12-inch pizza pan with 3/4-inch sides. Bake in a 350 degree F oven about 20 minutes or until just set in center.
Meanwhile, beat cream cheese, the 1/4 cup sugar, the 1 egg, and the 1/2 teaspoon vanilla until combined. Spread cream cheese mixture over hot brownie crust. Bake for 8 to 10 minutes more or until cream cheese mixture is set. Cover and chill for 4 to 24 hours.
Just before serving, arrange sliced bananas and sliced strawberries over cream cheese mixture. In a small heavy saucepan heat semisweet chocolate and shortening over low heat until melted; drizzle over fruit. Makes 12 to 16 servings.