1. Preheat oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving overhang for easy removal.

2. In a large bowl, cream together the softened butter and granulated sugar until fluffy. Add 2 cups flour and salt, mixing until crumbly.

3. Press mixture into prepared pan and smooth it evenly. Bake crust for 18–20 minutes, or until lightly golden. Let it cool slightly.

4. In another bowl, whisk together eggs, 1.5 cups sugar, 0.25 cup flour, lemon juice, and zest until smooth.

5. In a separate bowl, toss blueberries with 1 tablespoon flour. Gently fold them into the lemon mixture.

6. Pour lemon-blueberry filling over the pre-baked crust. Tap pan gently to distribute evenly.

7. Bake for 30–35 minutes, until center is just set and no longer jiggles.

8. Let bars cool completely at room temperature, then chill in the fridge for 2 hours before slicing.

9. Once firm, lift out using parchment and slice into squares. Dust with powdered sugar before serving.