Begin by placing a saucepan over low heat and adding unsalted butter. Stir gently until fully melted, then pour the melted butter over the white chocolate chips in a mixing bowl. Let the mixture sit for about 5 minutes to soften, then whisk it until smooth. Set it aside to cool for 30 minutes.

Once the chocolate mixture has cooled, whisk together the butter and chocolate with granulated sugar until fully combined. Add in the vanilla extract and eggs, mixing until smooth. Gently fold in all-purpose flour, salt, and fresh blueberries with a spatula, being careful not to overmix.

Preheat your oven to 350°F (175°C) and line an 8x8 inch baking pan with parchment paper. Pour the blondie batter into the prepared pan and spread it evenly with a spatula. Bake in the preheated oven for 35 to 45 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean or with a few moist crumbs.

After baking, remove the pan from the oven and let your Blueberry Blondies cool in the pan for about 10 minutes. Then, transfer them to a wire rack to cool completely, which will take about 30 minutes.

Once cool, cut the blondies into 12 to 16 squares, revealing the delightful bursts of blueberries within. Enjoy your delicious treats!