Mix graham cracker wafer crumbs, butter and brown sugar until well combined. Set aside 1/4 cup of this mixture for a topping and press the remainder into one 9x13 inch pan.
Bake at 350 degrees F (175 degrees C) for 10 minutes. Set aside to cool.
Dissolve raspberry gelatin in the boiling water and add the frozen raspberries, stirring until melted. Chill until partially set and spread on wafer base.
Melt marshmallows with the milk. When cool, fold in whipped cream and spread on top of raspberry mixture. Sprinkle with remaining crumbs. Chill for 3-4 hours before serving.
