My first ever dump cake. 2 thumbs up!
Place 3-4 cups thawed blackberries (juice drained) in a 9x13 baking dish. Mix 1/2 cup of sugar and 1 pack sugar free raspberry jello and sprinkle on top of the berries. Sprinkle 1 (dry) yellow cake mix over the jello. Melt 1/2 cup margarine and drizzle over the top. Slowly pour on 1 cup of water. Bake at 350 for 45-50 minutes or until toothpick comes out clean.
Top with whipped cream or vanilla .icecream