1Heat oven to 350°F (325°F for dark or nonstick pan). Grease bottom only of 13x9-inch pan with shortening or cooking spray. In large bowl, stir brownie mix, chocolate syrup, water, oil and 2 eggs until well blended. Spread batter in pan.
2In 2-quart saucepan, heat 3/4 cup whipping cream and the chocolate chips over medium heat, stirring constantly, until chocolate is melted and mixture is smooth; cool slightly. In medium bowl, beat 3 eggs and the granulated sugar with electric mixer on medium speed until foamy; stir into cream-chocolate mixture. Pour evenly over batter.
3Bake about 44 minutes, or until topping is set. Cool completely, about 2 hours. Serve at room temperature, or cover tightly and refrigerate until chilled. Serve dessert with whipped cream, if desired. Store in refrigerator.