I turned a classic pie into Easy Blueberry Pie Bars, and the secret twist in the crust is why I keep baking them.

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I can’t resist a dessert that looks fancy but behaves lazy. My Easy Blueberry Pie Bars blur the line between pie and bar, and the crust does double duty as the topping so you’re getting crisp edges and a soft center in every bite.

I love that the crust has old-fashioned rolled oats for texture and a scrape of lemon zest that makes the blueberry filling sing. Around here people call them Blueberry Pie Squares, and they always vanish fast.

Plus they travel great, if you bring them to a picnic they’ll be gone in minutes.

Ingredients

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All-purpose flour gives structure and a light chew, mostly carbs, little fiber.
Rolled oats add nuttiness and chew, good fiber and slow-burning carbs.
Brown sugar brings deep caramel sweetness and moistness, adds simple sugars.
Cold butter makes a tender crumb and richness, high in saturated fat.
Egg binds the crust, adds protein and moisture, but subtle flavor.
Blueberries give bright sweetness and tartness, they’re full of antioxidants and vitamins.
Lemon juice and zest lift fruit flavors, adds fresh acidity and brightness.
Cornstarch thickens the filling so it sets, neutral taste, mostly carbs.

Ingredient Quantities

2 cups all-purpose flour (about 250 g)

1 1/2 cups old-fashioned rolled oats (about 150 g)

1 1/4 cups packed light brown sugar

1/2 cup granulated sugar

1 tsp baking powder

1/2 tsp fine salt

1 cup (2 sticks) unsalted butter cold, cut into 1/2 inch cubes

1 large egg

5 cups fresh blueberries (about 20 oz) or frozen, thawed and drained

3/4 cup granulated sugar for the filling

3 tbsp cornstarch

2 tbsp fresh lemon juice

1 tsp lemon zest

1 tsp pure vanilla extract

Pinch of salt

Coarse sugar for sprinkling, optional

How to Make this

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1. Preheat oven to 375°F (190°C). Line a 9×13 inch pan with parchment paper and grease the sides so the bars lift out easy.

2. In a large bowl stir together 2 cups all purpose flour, 1 1/2 cups rolled oats, 1 1/4 cups packed light brown sugar, 1/2 cup granulated sugar, 1 tsp baking powder and 1/2 tsp salt.

3. Add 1 cup (2 sticks) cold butter cut into 1/2 inch cubes and cut it into the dry mix with a pastry cutter, two forks or pulse in a food processor until the mixture looks like coarse crumbs with pea sized bits. Add 1 large egg and stir just until the mixture holds together when you press it. Set aside about 1 1/2 to 2 cups of this mixture for the topping.

4. Press the remaining crumb mixture firmly and evenly into the bottom of the prepared pan to form the crust, use the bottom of a measuring cup to compact it well.

5. In another bowl toss 5 cups blueberries with 3/4 cup granulated sugar, 3 tbsp cornstarch, 2 tbsp fresh lemon juice, 1 tsp lemon zest, 1 tsp vanilla and a pinch of salt until berries are evenly coated.

6. Spread the blueberry mixture evenly over the pressed crust.

7. Sprinkle the reserved crumb mixture over the berries, breaking up any big chunks so you get a mostly even topping. If you like extra sparkle sprinkle coarse sugar on top.

8. Bake until the top is golden and the filling is bubbling, about 35 to 45 minutes. If the top browns too fast loosely tent with foil for the last 10 minutes.

9. Cool completely on a wire rack at least 2 hours so the filling sets, or pop it in the fridge for an hour for cleaner slices. Use the parchment overhang to lift the slab from the pan and cut into bars, wiping the knife between cuts helps.

10. Store leftover bars covered at room temp up to 2 days or in the fridge up to 4 days, you can also freeze them up to 2 months. Reheat briefly if you want them warm.

Equipment Needed

1. Oven (set to 375°F)

2. 9×13 inch baking pan lined with parchment and greased so the bars lift out easy

3. Large mixing bowl

4. Medium bowl for the blueberry filling

5. Measuring cups and measuring spoons

6. Pastry cutter or food processor or even two forks to cut in the butter

7. Rubber spatula or wooden spoon to stir and spread

8. Flat-bottomed measuring cup or small glass to press the crust firmly

9. Wire cooling rack

10. Sharp knife for slicing and a spatula to lift the bars out

FAQ

Q: Can I use frozen blueberries instead of fresh?
A: Yes. Thaw them first and drain off extra liquid, then toss gently with the sugar and cornstarch before adding to the pan. That helps keep the filling from getting too runny. You might need a minute or two extra baking time.

Q: How do I stop the bars from being soggy?
A: Pre-bake the crust about 12 minutes until it just starts to color, use the cornstarch in the filling, and make sure frozen berries are well drained. Let the bars cool completely so the filling sets before you cut them. Cutting while hot makes them fall apart.

Q: Can I swap the rolled oats for something else?
A: You can use quick oats or pulse rolled oats in a food processor so theyre finer. If you need a different crust entirely try graham cracker crumbs with melted butter, but the oat mixture gives that chewy, rustic texture you want.

Q: How long will these keep and can I freeze them?
A: Store at room temp for up to 2 days, or in the fridge for up to 4 days. For longer storage, freeze cut bars in a single layer and then stack in a bag for up to 3 months. Thaw in the fridge overnight.

Q: Can I make the bars ahead of time and bake later?
A: Yes. Make the crumb mixture and press half into the pan, keep the rest refrigerated. Add the filling then crumble the remaining topping on just before baking. You can also assemble and freeze unbaked, then bake from frozen adding a few extra minutes.

Q: I want less sweet or different fruit, what should I change?
A: For sweeter berries cut the filling sugar by 1/4 cup or so. For tarter fruit like rhubarb add a touch more sugar and keep the cornstarch amount the same. Apples or peaches work great too but may need slightly longer baking so the juices thicken.

Easy Blueberry Pie Bars! The Crust Does Double Duty As The Topping! Recipe Substitutions and Variations

All-purpose flour: try whole wheat pastry flour 1:1 by volume for a slightly nuttier, heartier crust, or use a gluten-free 1-to-1 baking blend same amount if you need GF. Chill the dough a bit longer since whole grain can be crumblier.
Old-fashioned rolled oats: swap with quick oats in the same amount; the bars will be softer and less chewy. Or pulse the rolled oats into coarse oat flour if you want a tighter, less rustic crumb.
Unsalted butter (cold): use chilled solid coconut oil 1:1 by volume or a vegan stick margarine 1:1. Coconut oil can add a faint coconut note, so keep it cold so the crust/topping holds its shape.
Cornstarch (for the filling): replace with arrowroot powder or tapioca starch 1:1. Arrowroot makes a clearer, glossy filling and works great with frozen fruit, tapioca gives a bit more chew.

Pro Tips

1. Keep the butter very cold and work fast so the crumbs stay pea sized and flaky. If the mix gets warm or greasy, pop it in the fridge for 10 to 20 minutes before pressing, you want a firm crust not a greasy mess.

2. If you use frozen berries, make sure they are fully thawed and well drained, then toss them with the cornstarch and sugar and let them sit for a few minutes so they start to macerate. Taste and add a little extra lemon or sugar if the berries are tart, it makes a big difference.

3. Press the crust really firmly into the pan with the bottom of a measuring cup so it holds together while baking. Bake until you see the filling bubbling in the center, and if the top is getting too dark cover it loosely with foil for the last bit.

4. Cool the bars completely before cutting, or chill them in the fridge for an hour for much cleaner slices; wipe the knife between cuts. Leftovers freeze great if you wrap each bar tight, and honestly they taste even better the next day.