Begin by melting ½ cup of unsalted butter in a medium saucepan over low heat. Once melted, stir in 1 cup of white chocolate chips until they are completely smooth. Remove the pan from heat and let the mixture cool for about 10 minutes.

In a large mixing bowl, combine the cooled butter-chocolate blend with 1 cup of granulated sugar and 2 teaspoons of pure vanilla extract. Whisk in 2 large eggs, one at a time, until the batter is smooth and fully combined.

Gently sift in 1 cup of all-purpose flour and ½ teaspoon of salt into the wet ingredients. Use a spatula to mix until just combined; be careful not to overmix, as you want the blondies to remain soft.

With a gentle hand, fold in 1 cup of fresh blueberries into the batter. Be cautious to avoid smashing the berries.

Preheat your oven to 350°F (175°C) and grease an 8x8-inch baking pan. Pour the batter into the prepared pan. Bake for 35-45 minutes until the top is golden brown and a toothpick inserted into the center comes out with a few moist crumbs.

Once baked, remove the Blueberry Blondies from the oven and let them cool in the pan on a wire rack for about 15-20 minutes. After they have cooled, cut them into squares and serve warm or at room temperature.