Bake brownies as directed (the 9x13 size). Let cool for at least an hour on the counter, or a half hour in the refrigerator.
Mix together 1/2 cup of almost melted butter (you don't want it liquid, but you want it extremely soft), powdered sugar, milk, and raspberry extract. Add as much red food coloring as is necessary to get it a nice pink color. Pour the mixture over the cooled brownies, spreading to make a nice even layer. Refrigerate for another half hour.
Melt the chocolate chips and the remaining 1/2 cup butter over medium low heat, stirring until smooth. Pour over the brownies, tilting the pan so it smooths out. Refrigerate for an hour or until chocolate has completely set and is hard.