°1 pack (18.25 oz) yellow cake mix
°1 c water
°⅓ c vegetable oil
°½ c white sugar
°1 tsp cornstarch
°2 cup freshly blueberries
°1 pack (16 oz) icing sugar
°1 pack (8 oz) cream cheese, softened
°¼ teaspoon vanilla extract
°1 container (8 oz) frozen whipped topping, thawed
*Step by step
Preheat oven 350 degrees F (175 degrees C). Butter a 9 x 13 inch baking dish.
Beat cake mix with 1 cup water, eggs and vegetable oil until smooth; pour into prepared baking dish.
Bake in preheated oven until toothpick inserted in center comes out clean, 23 to 28 minutes. Let cool in pans for 10 minutes before removing to cool completely on a wire rack. Cut the cake in half horizontally to make 2 layers.
Combine white sugar and cornstarch in a saucepan; gradually stir in 1/3 cup water. Add the blueberries and bring to a boil over medium heat. Simmer until thickened, stirring occasionally, about 1 minute. Let the blueberry mixture cool.
Beat icing sugar and cream cheese in large bowl until smooth. Stir in vanilla extract and stir in whipped topping.
Place cake layer on large platter; spread blueberry mixture over cake. Arrange remaining cake layer over blueberry filling. Spread the cream cheese frosting all over the cake.