Chef notes

When it comes to baking, blueberries are the superior berry. They’re not as watery as strawberries or noticeably seedy as raspberries and blackberries. Plus, they pretty reliably cook down to the same consistency every time. Not to mention, they’re just as delightful and flavorful when cooked as they are fresh. Enter these blueberry pie bars.

Easily shareable and with the feel of a summery streusel-topped pie, these blueberry pie bars are perfect for spring picnics, summer barbecues and everything in between. One oat-studded dough doubles as both the bottom press-in crust and streusel topping for the bars. Unlike other pie bar-style recipes which par-bake the crust, these are simply baked in one shot. The crust is still perfectly golden, delightfully tender and holds up to the jammy blueberries.

Just like with classic fruit pies, the key to nailing that sliceable consistency is to bake the bars until the filling is bubbling around the edges. Cornstarch helps to thicken the filling to the perfect jammy texture.. For the perfect slices, make sure to completely cool the bars before cutting.

Technique Tip: Rubbing the lemon zest into the sugar releases the oils from the zest, permeating the pie with lemon to help brighten and bring out the flavor of the blueberries.

Swap Option: You can use frozen blueberries in place of fresh, but the filling will have a stiffer, jammier consistency. Do not thaw the frozen berries.

You can use a smaller, 8-inch square baking pan if you do not have a 9-inch pan, but you may need to bake the bars a few minutes longer.

Ingredients

For the Streusel

nonstick cooking spray, for greasing the pan
14 tablespoons unsalted butter, room temperature
1/3 cup granulated sugar
1/3 cup packed light brown sugar

1 teaspoon pure vanilla extract
1⅔ cups all-purpose flour
1/2 cup rolled oats
1 teaspoon kosher salt

For the Filling

2 teaspoons lemon zest, from 1 lemon
3 tablespoons granulated sugar
18 ounces fresh blueberries
1½ tablespoons cornstarch

1½ tablespoons lemon juice, from 1 lemon
1 teaspoon pure vanilla extract
1/4 teaspoon kosher salt
confectioners’ sugar, for dusting (optional)

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Preparation

Make the streusel

Preheat the oven to 375 F with a rack positioned in the lower third. Lightly grease a 9-inch square baking pan with nonstick cooking spray. Line the pan with parchment paper, leaving a slight overhang on all sides.

In a large bowl with an electric hand mixer, beat together the butter, granulated sugar, light brown sugar and vanilla on medium speed until combined and fluffy, 1 to 2 minutes.

Add the flour, oats and salt and beat on low until just combined and the mixture is crumbly, but clumps when squeezed, about 30 seconds.

Spread 2¼ cups of the streusel mixture in the prepared pan and press down into an even layer. Place the pan and remaining streusel mixture in the refrigerator while you prepare the filling.

Make the filling

In a large bowl, use your fingers to rub the lemon zest into the sugar until fragrant. Add the blueberries, cornstarch, lemon juice, vanilla and salt and toss with a spoon or rubber spatula until glossy and the sugar and cornstarch are dissolved.

Arrange the blueberries in an even layer over the chilled crust. Top with the rest of the streusel mixture.

Bake for 50 to 60 minutes or until the streusel is golden brown and the filling is bubbling around the edges.

Place the pan on a wire rack and cool completely.

Lift the slab out by the parchment overhang and transfer to a cutting board. Lightly dust with confectioners’ sugar, if using.