Melt stick of butter in glass pyrex dish in oven at 350 degrees. While butter is melting, mix milk, flour and sugar in bowel. Add tsp of vanilla to mixture. On stove top mix 1 cup of water,1/2 cup of suger,1 tsp vanilla and 1Tbsp of cornstarch. Cook until mixture becomes syrupy about 5min or so. Pour flour mixture over butter. Last pour blackberry mixture over flour mixture. Bake at 350 until mixture slightly browns.