Preheat oven to 350°. Lightly spray a 9×9-inch baking pan with nonstick spray. Line bottom of pan with graham crackers, cutting crackers as needed.

Prepare brownie batter according to package directions using eggs, oil and ¼ cup cold water. Spread batter in an even layer on top of crackers in pan. Bake 38 to 40 minutes or until a toothpick inserted near center comes out clean. Cool brownies in pan on a wire rack.

Combine remaining ½ cup water, granulated sugar, meringue powder, and vanilla in a mixing bowl. Beat with an electric mixer on high 7 to 9 minutes or until stiff peaks form (tips stand straight). Spread mixture over cooled brownies.

Place oven rack 6 inches from heat. Preheat broiler to HIGH. Broil 3 to 5 minutes or until meringue mixture is lightly toasted. Store covered up to 3 days at room temperature.