1/3 c. granulated sugar
1/3 c. brown sugar, packed
2 tbsp. minute tapioca
1/4 tsp. salt
3/4 c. water
2 tbsp. lemon juice
2 tsp. vanilla
2 c. fresh or frozen blueberries
1 c. biscuit mix
1/3 c. granulated sugar
1 egg
1/3 c. milk
3 tbsp. or butter, divided

Preheat oven to 350 degrees. Grease shallow 1 1/2 quart baking dish. Combine sugars, tapioca, salt and water. Cook, stirring constantly until mixture comes to a boil. Remove from heat, stir in lemon juice, 1 tablespoon of the butter and the blueberries. Pour into the prepared dish. Combine the biscuit mix, sugar, egg, milk, vanilla and the remaining butter. Beat with electric mixer at low speed until blended (about 30 seconds). Beat at medium speed 4 minutes, scraping sides of bowl. Spoon over warm blueberry mixture, spreading evenly. Bake in moderate 350 degree oven for 35 minutes or until cake is golden and springs back when lightly pressed with fingertip.