Prepare the Oven and Pan: Preheat the oven to 350°F (177°C). Line an 8x8 inch square baking dish with parchment paper, leaving an overhang on the sides. Lightly coat with non-stick spray.

Melt the Butter and White Chocolate: Melt the butter in a saucepan. Pour the hot butter over the white chocolate chips in a heat-safe bowl. Let it sit for five minutes, then stir until smooth. Allow the mixture to cool for thirty minutes until it thickens.

Mix the Wet Ingredients: Combine the cooled butter mixture with granulated sugar in a large bowl. Whisk well. Add the vanilla extract and eggs, whisking until the batter is smooth.

Incorporate the Dry Ingredients: Add the flour and salt. Use a silicone spatula to gently fold the dry ingredients into the wet mixture just until combined.

Fold in the Blueberries: Gently fold the fresh blueberries into the batter, taking care not to crush them.

Bake to Perfection: Spread the batter into the prepared pan. Bake until the edges are caramelized and the top is golden brown. A toothpick inserted into the center should come out clean.

Cool and Serve: Let the blondies cool completely in the pan at room temperature to set. Lift out using the parchment paper and cut into squares.