Bake the brownies according to the package directions, adding the extra egg, substituting water for milk and using an 8-inch square baking pan. Cool completely.
Meanwhile, put the raspberries, 1/4 cup of super-fine sugar and the salt in a blender and puree until smooth. Push through a sieve with a rubber spatula; discard the seeds. (The raspberry coulis can be made 3 days in advance and stored, covered, in the refrigerator.)
Whip the heavy cream with the remaining 1/2 cup super-fine sugar until soft peaks form. Cut out four 3-inch round circles from the brownies. Pour some raspberry coulis in the centers of 4 dessert plates and top each with a brownie round. Dollop with heavy cream, garnish with raspberries and serve.
You can crumble the trimmings from the brownie rounds and use them to top ice cream.
Recipe courtesy of Haylie Duff