Combine cake mix, egg, zest, juice and butter in an electric mixer. Pat into a lightly greased 9 x 13 x 2 pan.
Rinse blueberries and spread over crust in a single layer.
Next, using an electric mixer, beat cream cheese and butter until smooth, add eggs, lemon juice, zest and vanilla. Dump in confectionery sugar and beat well. Mix well.
Pour onto cake mixture and spread evenly.
Bake at 350* for 60 minutes. It should remain a little gooey in the center. Cool completely and cut into squares. I baked mine at 325 and it took just over an hour. I started checking it at 45 minutes.
Recipe by Recipes Food and Cooking at https://recipesfoodandcooking.com/2016/11/16/ooey-gooey-lemon-blueberry-cake/