Blackberry Pie Bars

Everything you love about blackberry pie, in an easy-to-make, easy-to-share, bar form.  Blackberry Pie Bars are the perfect way to highlight summer’s best berry!

These blackberry pie bars were one of the first recipes ever posted on Bunsen Burner Bakery, allll the way back in August 2011. 

They were getting a little lost back in the archives, so I thought it was time to spruce up the post a bit — new photos, a few recipe tweaks (I’ve learned a thing or two about baking over the past 8 years!), and some new tips and tricks before featuring them back on the front page.

Now that we’re finding fresh blackberries in the stores again, it seemed like the perfect time to republish these easy blackberry pie bars.  One thing that hasn’t changed over the past 8 years: my love of fruit dessert and pies.  These are still a favorite!

What are Pie Bars?

Pie bars take the best parts of pies: the crispy crust, the delicious fruit filling — and put them in dessert bar form!  Easy to make, portable, and perfect for sharing!

I love rolling out pies.  (Obviously — I did a yearlong series on pies last year!)  But let’s be honest: pie is not the best dessert to share with a crowd.  At a sit-down dinner, sure — but to bring to an event where people might be milling around with a plate in one hand?  Not so much.

Let’s talk about what these pie bars bring to the table.  A buttery crust?  Check.  A custard-like blackberry filling, combining the texture of a cream pie with the flavor of a fruit pie?  Check.  A crumble-like topping holding everything together?  Check again!

Shortbread Crust + Blackberry Custard

First up: the crust.  It’s an easy shortbread-style recipe, made by mixing ingredients together with a mixer.  No cutting in butter, no rolling.  Just mix together and press into the bottom of the pan. 

We’ll then par-bake the crust, meaning we’ll bake the crust empty.  This ensure the crust stays crisp and firm, even after we pour the liquid custard on top.

The filling for this custard is a starch-thickened custard, meaning the eggs are set with the help of a starch — in this case, flour.  Why do we want to add starch to our custard for these blackbery pie bars?  It’s time for my favorite subject… kitchen chemistry!

Kitchen Chemistry

Adding starch (like flour) to a custard slows the coagulation of the egg proteins as they heat, preventing overcooking and curdling.  A startch-thickened custard must reach a simmering point to properly denature the amylase enzyme in the egg yolks.

Using a starch-thickened custard allows us to bake the blackberry pie bars at a higher temperature.  We can fully cook the crumble on top of the bars, but the filling stays nice and creamy.  No curdling, no need for a water bath.  It also makes the custard thicker — meaning we can slice these bars and the filling will hold its shape!

The custard is super easy to make, since we’ll be cooking it in the oven and not on the stovetop.  Whisk together eggs, sugar, sour cream, flour, lime juice, lime zest, and salt. 

Lemon seems to be a common flavor to pair with blackberry desserts, but I love using lime instead.  Lime is such a great flavor for summery desserts.  Plus, blackberries and limes are such a good combination — hello, blackberry mojitos!

Fruit Substitutions

Two common questions: can you use frozen blackberries or can you substitute in other fruits?  Yes and yes!

If you’re using frozen blackberries instead of fresh, you’ll want to thaw and drain the blackberries first.

As for other fruit substitutions: of course!  Blueberries or raspberries are a natural swap.  Strawberries work too, but you’ll want to cut the strawberries down into pieces closer in size to a blackberry or blueberry.

I have not personally tried these with peaches, but I think using pieces of peaches would be a delicious option, too!

How to Store Blackberry Pie Bars

Because of the custard component, blackberry pie bars are best stored in the refrigerator.  While these can be consumed at room temperature, we actually found that we like the flavor and texture best coming straight from the fridge.

Made too many?  These blackberry pie bars freeze beautifully as well!  Cut into individual bars, then wrap in plastic wrap followed by a layer of aluminum foil and store in an air-tight freezer bag.  Thaw in the refrigerator before eating.

Tips and Tricks for Blackberry Pie Bars

1. If you’re using frozen blackberries, thaw the berries and drain excess liquid first.  The easiest way to do this is thaw on a plate overnight in the refrigerator.
2. Ensure your butter is cold and cubed when making the crust and crumble topping. This will create a flakier texture.
3. To prevent a soggy bottom, prebake the crust for 15 minutes before adding the blackberry filling. This helps maintain a crisp texture.
4. After baking, allow the bars to sit for at least an hour before slicing.  This ensures the custard center will fully set.
5. These blackberry pie bars are extremely rich, so cut the bars into small pieces.  (All the better for sharing with more people!)

More Dessert Bar Recipes:

• Lemon Pie Bars
• Gooey S’mores Bars
• Cranberry Lime Bars
• Berry Oatmeal Crumble Bars
• All Dessert Recipes »

This recipe was originally published in August 2011 and republished with updated text and photos in June 2019.