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Blackberry Slab Pie Bars

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blackberry slab pie bars, stacked

Blackberry Slab Pie Bars ~ the flakey pastry, the jewel toned filling, and the sweet little glaze all work together in this super user friendly dessert.  They can go from your end-of-summer bbq bash to your holiday dessert tables, just use frozen fruit or preserves when fresh berries aren’t available.

blackberry slab pie bars

Give me a slab pie bar over over a slice of pie any day, they’re just so much more user friendly.  You can pick these bars up with your hands, tote them around with you, bring ’em on a driving trip, to work, on a plane…what pie can do all that?  And these bars are just as flaky, just as fruity and juicy as any pie.  Plus they’ve got a sweet glaze layered over top.  

a stack of blackberry slab pie bars on parchment paper

I used one of my favorite pastry doughs for these blackberry bars.  It’s the dough I used in my Apricot Pie Recipe, and it’s easy to work with, super flaky, with a really lovely softness to it.  It’s made with mostly butter and a little shortening which I think makes the difference. It bakes up firm enough so that you can eat these bars by hand, but still quite tender when you bit into it.

This is the perfect recipe for a pie-crust-a-phobe (like me!)

The dough is easy to roll and forgiving, just push it back together if it cracks, and dust with flour if it sticks.  I like to roll it right on the parchment paper it will bake on, so there’s no tricky transfer to deal with, just slide the dough and paper right onto a baking sheet.

This is a free-form format, so roll it out into a rough rectangle (or oval!) and it will be fine.  You’ll trim off the edges before slicing, anyway.

making blackberry slab pie bars

But these pie bars would be nothing without the fresh blackberry filling.  I made a quick jammy filling by cooking down the berries on the stove with some sugar, lemon juice and thickener.  

blackberries with sugar

Blackberries go through a beautiful color transformation when they’re cooked with lemon juice and sugar, the deep blueish purple becomes a brilliant magenta. It’s absolutely gorgeous oozing out of the layers of pastry dough.

You can use a good blackberry jam or frozen berries to make your filling off season.

cooking blackberries

For the thickener I’ve recently discovered Instant Clearjel, which is a super thickener for pies and fruit fillings.  It works like cornstarch, but so much better, and it gives you an added insurance that your fillings won’t be too thin or runny.

blackberry filling for blackberry slab pie bars

This kind of freeform slab pie doesn’t look like much in its whole form, it’s a little ragged, I admit. But do try it, I know you’ll be pleased.

glazing and cutting blackberry slab pie bars

The flakey pastry, the brilliant filling, and the glaze all make this one of my new favorite desserts on the blog.  I’m going to be doing an apple version for you later this month, so keep an eye out for that.  

Be sure to freeze summer berries so you can make this later in the year ~

  • Wash and dry your berries and lay them out in a single layer on a parchment lined baking sheet.  
  • Put the whole pan in the freezer until the berries are frozen solid, about an hour.  
  • Transfer the berries to a heavy duty zip lock freezer bag and put them back in the freezer.  They’ll keep up to a year.

a blackberry slab pie bar on a napkin with forks

Other blackberry recipes you’ll definitely want to check out before you go!

blackberry slab pie bars, stacked
Add to Your Recipe Box
3.71 from 31 votes

Blackberry Slab Pie Bars

Blackberry Slab Pie Bars ~ the flakey pastry, the jewel toned filling, and the sweet little glaze all work together in this super user friendly dessert.  They can go from your end-of-summer bbq bash to your holiday dessert tables, just use frozen fruit or preserves when fresh berries aren't available.
Course Dessert
Cuisine American
Prep Time 2 hours 15 minutes
Cook Time 40 minutes
Yield 16 servings


pie crust

  • 2 1/2 cups all purpose flour, plus more for rolling
  • 1 tsp salt
  • 3/4 cup (1 and a half sticks) unsalted butter, cold and cut in pieces
  • 1/4 cup shortening (I used butter flavor Crisco)
  • 1/4 cup ice water


  • 12 ounces fresh blackberries
  • 1/2 cup sugar
  • 2 tsp Instant Clearjel thickener (substitute 1 Tbsp cornstarch)
  • juice of 1/2 lemon


  • 1 cup confectioner's sugar, sifted
  • water for thinning


  • Start by making the crust. Pulse the flour and salt a few times in a food processor to combine. Add the cold chunks of butter and shortening to the bowl and pulse about 20 times until the mixture is grainy.
  • Add the ice water, a little at a time, while continuing to pulse, until the dough just comes together when you pinch it between your fingers. Stop the machine to check it. NOTE: you may not need all of the water, but I always do.
  • Turn the dough out onto a floured surface and bring it together into a ball. If there is still any remaining dry flour make sure to knead that into the dough to get it all incorporated. If your dough is too sticky, add a touch more flour.
  • Cut the ball of dough in half, form two flat rectangles, and wrap each one in plastic. Refrigerate the dough for 2 hours (or overnight) before rolling it out.
  • While the dough is chilling make the filling. This step can also be made the day before if you like. Put the berries into a saucepan. Mix the sugar and Clearjel thickener together and add to pan along with the lemon juice. Starting on low and then increasing the heat to medium high, cook the berries until they start to soften and the sugar has dissolved. Mash the berries with a fork as they soften. Stir almost constantly.
  • Cook for about 8 minutes, or until it's the consistency of a runny jam. I like to mash most of the berries. Chill the filling until ready to use.
  • Preheat the oven to 350F
  • Lay out a sheet of parchment large enough for a baking sheet and lightly flour it. Roll out one of the pieces of dough to (roughly) a 9x13 rectangle. Don't stress, if it's close, that's fine. It helps to let the dough rest for a few minutes to warm up slightly before trying to roll it out.
  • Spoon the jam over the top, leaving about an inch all around free.
  • Roll out the top crust, and carefully place over the jam filling, pressing down all around the edges to seal. if you've got excess dough you can roll it up a bit.
  • Brush with the egg wash and bake for about 40 minutes until golden. Let cool before glazing.
  • To make the glaze whisk or stir the sugar together with the water, a tablespoon at a time, until you get a glaze consistency. Brush it liberally over the top of the cooled pie. Let dry before slicing.

blackberry slab pie bars pin


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    Leave a Reply

  • Reply
    January 30, 2020 at 3:33 pm

    Can you strain the seeds out of the berry mixture?

    • Reply
      January 31, 2020 at 2:28 pm

      Hi Debbie ~ yes, you should be able to push the filling through a fine mesh strainer to get the seeds out! I’d do this while the mixture is still warm as it will thicken up and get harder to strain as it cools.

  • Reply
    Martha in KS
    September 7, 2019 at 5:23 am

    I used to freeze blueberries using this method until I brought home a bunch of berries & didn’t have time to do it. So I stuck the plastic containers of berries right into the freezer. A few days later I dumped them into plastic bags. When I need them I rinse & use. Now that’s how I always freeze them. No need for the pre-freezer prep!

    • Reply
      September 7, 2019 at 8:30 am

      Good to know! I would think if the berries were dry with no moisture this would work fine.

  • Reply
    Tricia B.
    August 30, 2019 at 4:35 am

    I LOVE this freeform slab pie! And that filling is fantastic. We’re all about fresh fruit desserts and I can’t wait to give this a try. Looking forward to the apple version too! Pinned

    • Reply
      August 30, 2019 at 6:02 am

      Thanks Tricia, I’m looking forward to the apple version too!