Preheat your oven to 350 degrees Fahrenheit.
For the base: In a large bowl combine flour, brown sugar, salt, and cinnamon. Cut in butter with two forks until you are left with a crumbly mixture.
Line a 9 x 9 inch square pan with foil hanging over the sides so that you will be able to easily remove the cheesecake bars from the pan. Spray the foil with non-stick cooking spray. Press the crust mixture into the pan and press down firmly. Bake for 15-18 minutes until it just starts to turn a light golden brown color. Allow the crust to cool.
While the crust bakes, make the streusel topping: in a medium bowl combine 1/2 cup packed light brown sugar with 1/2 cup all purpose flour, 1/4 teaspoon cinnamon, and 1/4 cup quick cooking oats. Use two forks to cut 1/4 cup butter into the mixture. When crumbly, sprinkle the mixture over the cheesecake.
For the cream cheese layer: With your mixer, beat the cream cheese with 1/2 cup sugar until smooth, about 2 minutes. then add in eggs, one at a time, then vanilla.
Add in the zest and juice from 1 lemon. Mix well.
Fold in half of the blueberries.
Pour the mixture on top of the crust and spread it out evenly.
Press the remaining blueberries on top.
Sprinkle the streusel topping over the blueberries.
Bake for about 35-40 minutes, until the filling has set and just the center is still a bit jiggly. Cool to room temperature for about an hour, then continue chilling in the fridge for about 3 hours.
Remove the cheesecake bars from the pan by lifting the foil out.
Cut into pieces and serve.