Blueberry Pie Bars with Flaky Pastry

Prep Time: 25 minutes
Cook Time: 40–45 minutes
Cooling Time: 2 hours
Servings: 9 large bars

These bars are inspired by the photo: a firm, buttery base, a thick layer of dark berry filling, and a golden, flaky pastry top. Cooling them completely is the key to getting clean squares.

Ingredients

For the base

• 1½ cups all-purpose flour
• ¼ cup granulated sugar
• ½ cup unsalted butter, melted
• ¼ teaspoon salt

For the blueberry filling

• 3 cups fresh or frozen blueberries
• ½ cup granulated sugar
• 3 tablespoons cornstarch
• 1 tablespoon lemon juice
• 1 teaspoon vanilla extract
• Pinch of salt

For the top

• 1 sheet frozen puff pastry, thawed according to package directions
• 1 egg beaten with 1 teaspoon water, for brushing
• 1 teaspoon coarse sugar, optional

Instructions

1. Prepare the pan. Preheat the oven to 375°F (190°C). Line a 9-inch square baking pan with parchment paper, leaving enough overhang on two sides to lift out the bars later.
2. Make the base. Stir together the flour, sugar, melted butter, and salt until the mixture forms a soft, crumbly dough. Press it firmly and evenly into the prepared pan. Bake for 15–18 minutes, until the edges are lightly golden. Set aside.
3. Cook the filling. Add the blueberries, sugar, cornstarch, lemon juice, vanilla, and salt to a saucepan. Cook over medium heat, stirring gently, for 6–10 minutes. The berries should release their juices and the mixture should become thick and glossy. If using frozen berries, allow a few extra minutes. Remove from the heat and let cool for 10 minutes.
4. Assemble the bars. Increase the oven temperature to 400°F (200°C). Spread the blueberry filling evenly over the baked base. Lay the thawed puff pastry over the filling, trimming it to fit inside the pan. Cut a few small slits in the pastry so steam can escape. Brush with the egg wash and sprinkle with coarse sugar, if using.
5. Bake. Bake for 22–27 minutes, until the pastry is puffed and deep golden brown. If it browns too quickly, loosely cover the top with foil for the final few minutes.
6. Cool and slice. Let the bars cool completely in the pan, then refrigerate for at least 1 hour to firm up the filling. Lift them out using the parchment and cut into 9 squares with a sharp knife.

Tips

• The filling should be quite thick before it goes into the pan; a runny filling will make the bars difficult to slice.
• Keep the puff pastry cool until you are ready to use it so it rises well in the oven.
• For a mixed berry version, replace up to 1 cup of blueberries with raspberries or blackberries.

Storage

Store the bars covered in the refrigerator for up to 4 days. The pastry is crispest on the day they are made. To refresh a bar, warm it briefly in a 325°F (165°C) oven.