In a medium saucepan over medium heat, melt ½ cup of unsalted butter, stirring occasionally until fully liquefied. Once melted, pour the butter over 1 cup of white chocolate chips in a mixing bowl and let it sit for 5 minutes. Stir until the mixture is well combined and smooth, then set aside to cool for 30 minutes.

In a large bowl, whisk together the cooled butter-chocolate mixture with 1 cup of granulated sugar until evenly blended. Next, add 1 teaspoon of pure vanilla extract, incorporating it into the mix. Crack in 2 large eggs and whisk until the mixture is smooth and glossy.

Gently fold in 1 cup of all-purpose flour and ¼ teaspoon of salt into the wet ingredients, mixing just until no dry streaks remain. Carefully add 1 cup of fresh blueberries, ensuring they are evenly distributed throughout the batter.

Prepare an 8x8 inch baking pan by lining it with parchment paper or greasing it well. Pour the blondie batter into the pan, spreading it evenly. Bake in a preheated oven at 350°F for 35-45 minutes.

Once baked, remove the pan from the oven and allow the Blueberry Blondies to cool completely in the pan for about 30 minutes. Once cooled, cut them into 12-16 squares and serve warm or at room temperature.