• Preheat oven to 350°F. Grease a 9x13 pan very well, set aside.
• In a large bowl, whisk together cake mix and pudding mix. Add sour cream, milk, oil and eggs and beat until smooth.
• Pour into prepared pan and bake for 23-25 minutes or until a toothpick inserted into the center comes out clean.

For the blueberry syrup

• In a medium saucepan, add blueberries, sugar and lemon juice. Simmer on medium-low heat for 5 minutes or until the natural juices start flowing. Mash them down a bit so more of the juice comes out. Turn stove to low heat and simmer another 5 minutes. Mash one more time then strain through a fine mesh strainer over a bowl to remove all blueberry pieces, you only want the syrup. Allow to cool a bit until the cake is done baking.
• Once cake is done, allow it to cool until warm then poke holes across the entire surface of the cake. Pour blueberry syrup into all of the holes making sure to fill each hole - it will not fill all the way to the top of each hole. Place cake in the refrigerator and chill until cold, about 1 hour.

For the frosting

• Beat whipped topping, powdered sugar and lemon juice until smooth. The frosting will be quite thin. Smooth over the cooled cake and place back in the refrigerator to firm up for 3 hours.