Preheat your oven to 350°F (175°C). In a mixing bowl, combine the brown sugar, flour, and chopped pecans. Pour in the melted butter and stir until fully combined. Press this mixture firmly into the bottom of a baking dish to create an even layer. Bake for 15 minutes, or until the crust is golden brown. Once done, remove it from the oven and allow it to cool completely.

In a small bowl, beat together evaporated milk and the instant lemon pudding mix until it thickens. In a larger mixing bowl, blend the cream cheese until fluffy and smooth. Gradually mix in the frozen lemonade concentrate, followed by the thickened pudding mixture, ensuring everything is well incorporated. Spoon this creamy and tangy lemon filling over the cooled crust, smoothing it out with a spatula.

In a medium saucepan over medium heat, combine fresh blueberries, granulated sugar, lemon juice, and cornstarch. Cook while gently stirring until the blueberries start to burst and the mixture thickens, approximately 5–7 minutes. You want the sauce to be bubbly and glossy. Once thickened, remove from heat and let it cool completely before spooning it over the lemon filling.

Cover the assembled dessert with plastic wrap and refrigerate it for at least 4 hours—or overnight if possible. This chilling time allows the flavors to meld beautifully and the filling to set properly.