Preheat oven to 350ºF. Line a 9x13" baking pan with parchment paper and spray with nonstick cooking spray.
In a large bowl, mix together the dry cake mix, 1 egg and 1/2 cup of butter (1 stick).
Press the mixture into the bottom of the prepared pan in an even layer. Set aside.
In another bowl, use an electric mixer to beat the cream cheese until smooth.
Add in the remaining 2 eggs, vanilla and 1/2 cup butter. Mix on low speed until combined, scraping the sides of the bowl as needed.
Mix in the powdered sugar on low speed until smooth.
Fold in the lemon zest and blueberries, reserving about 1/2 cup of blueberries for the top of the dessert.
Spread the cheesecake mixture on top of the crust in pan. Then sprinkle with remaining blueberries.
Bake for about 35-40 minutes or until center is set but still gooey. The edges of the cake will be very lightly golden brown.
Remove from oven and let cool completely.
Sprinkle with powdered sugar.
Cut into bars and store in an airtight container in the refrigerator for up to 4 days. You can also freeze the bars. Place in an airtight container in the freezer for up to 2 months.
Video
Notes
It can be melted butter or just very soft butter.
The calories shown are based on the cake being cut into 16 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information.**