Blackberry Crumble Bars

Occasionally, I’ll get the urge to throw together a picnic. Even if the weather isn’t that great and I hadn’t planned on going on a picnic, I just want to feel that cozy Spring vibe that only a picnic can produce. Something about eating outside in the calm, quiet sunshine just speaks to the best of us, and no picnic is complete in my book without the feature of berries in some fashion. Yes, I’ll go for strawberries, raspberries, or blueberries, the typical stars of the show, but there are plenty of times I’ll go out of my way to reach for the humble blackberry instead.

Blackberries are an incredibly undervalued and underrated berry in the baking world, often overlooked for their bright red rival, the raspberry. And it’s a shame. Blackberries offer just as big of a tart punch as raspberries, with their own unique flavor to work with. They balance out the intense sweetness of something like white chocolate as well as any raspberry, and shine from the brightness of added citrus in their own harmonious way. This is a pro blackberry household.

Thus, these blackberry crumble bars were born. They’re just the right level of tart, with warmth from the spices and crunch from the crumble topping, and thanks to the use of frozen berries, can be deliciously crafted any time of year. It’s like having a blackberry pie but in bar form, making it easier to both bake and consume. Perfect for packing up in that picnic basket!

FAQs and Science

Why prepare the crust using the creamed butter method, rather than pouring melted butter into the dry goods?

It makes a massive difference to the texture which method you use to prepare the crust. Adding melted butter to the dry goods would result in a crispy, crumbly shortbread, whereas the creamed butter method yields a much softer and more structured product. In this case, the softer texture is preferred.

Why only add spices to half of the crust, rather than all of it?

During testing, I found that the flavor was better with just a spiced top crust, but you’re in charge of your own bars. If you’d rather just add the spices with the rest of the dry goods, go for it! Maybe you’ll like it just fine, or maybe you’ll agree and try it as I’ve suggested next time.

Would it make a difference if I used fresh blackberries instead of frozen?

Frozen blackberries, in addition to being the cheaper option, result in a more jammy texture in the end, whereas fresh blackberries stay more whole in the final product. Texture-wise, the frozen blackberries work better, but if you find yourself with a ton of fresh blackberries that you need to use up, it wont ruin anything to do so!

Does it matter if the lemon juice is fresh or from a bottle?

I will always advise for you to use fresh citrus juice in any recipe I create, as the flavor is much better. But if you’ve run out of lemons and only have the bottled stuff, don’t worry about it. The lemon isn’t the star of the show, it’s only a Tablespoon put there for brightness. Your bars will still be delicious.

What You’ll Need

8×8 inch baking dish
Parchment paper
Stand mixer fitted with paddle attachment
Dry measuring cups
Measuring spoons
Small mixing bowl
Large mixing bowl
Whisk
Rubber spatula
Chef’s knife
Cutting board

The Process

Prepare the Crust

Begin by preparing the shortbread crust. This crust is designed to be a soft shortbread, rather than a crumbly mess. The crumbly mess is delicious, but it’s not the easiest consistency of dough to get to cooperate and isn’t the mouthfeel I was aiming for when creating the recipe. Preheat the oven to 350F, on the convection setting if possible, and prepare an 8×8 baking dish. Line the bottom and up the sides of the dish with parchment paper, making sure the parchment extends 1-2 inches above the top of the pan, and set it aside. This way, when the bars have finished baking, that gooey bubbling filling wont prevent you from getting the bars out of the pan.

In a small mixing bowl, whisk together the flour and salt, and set them aside.

In a stand mixer, using the paddle attachment, cream together the softened butter. granulated sugar, and vanilla on level 3 or 4 for 4-5 minutes. It should go from a pale yellow to almost white in color, and very fluffy in texture.

Add the flour mix to the stand mixer all at once, and beat it on level 1 for a minute to incorporate. Add 3 Tablespoons of whole milk to the dough, and beat once more on level 1 until it’s just incorporated, about a minute. Be careful not to over-mix the dough, or it will develop too much gluten and become tough. These bars were meant to be delicate, give them a fighting chance.

Remove half of the dough and press it firmly and evenly into the bottom of the prepared 8×8 pan. Blind bake the bottom crust for 15-20 minutes, or until the edges turn a light golden brown. Par-baking the bottom crust now is absolutely crucial. If you don’t, it wont bake all the way through unless the top layers have burned.

To the remaining half of dough in the stand mixer, add the cinnamon and allspice. I did toy with mixing spices into both the bottom and the top layer of dough, but it honestly was overpowering. Only including spices in the top layer of dough resulted in a better balance of flavors. If the dough seems a bit dry, add up to 1 Tablespoon more of the whole milk. Cover the dough, and set it aside.

Prepare the Filling

While the crust bakes, make the filling. In a small mixing bowl, whisk together the sugar, corn starch, and salt. Set it aside. In a large mixing bowl, add the frozen blackberries and the sugar mixture you just made.

Gently toss the berries in the sugar to coat completely, and add in the lemon juice. The lemon will not only help the dry goods to stick to the berries, but it will add some delightful brightness. Stir the filling until the lemon juice has saturated the sugar mixture coating the berries, and set it aside.

Once the crust has finished its par-bake, remove it and immediately pour the filling over top, spreading evenly to coat the entire thing. Don’t worry if it looks like there are some gaps without berries. Once the blackberries cook, they’ll spread out and fill the spaces.

Take the spiced dough and sprinkle large chunks of it over the filling. Don’t worry about the pieces being different sizes, it only adds to the rustic charm. Cover as much of the top as you can, and place it back in the oven to bake for 30-35 more minutes or until the top crumbles are golden brown and the filling is bubbling. It will spill over the top crust a bit, that’s okay!

Allow the filling to cool in the pan for 15 minutes, then gently remove the slab from the pan. If you remove the bars too soon, they’ll fall apart on you. But if you allow them to cool completely in the pan, you run the risk of them sticking to the sides, making them difficult to remove, Use the parchment paper hanging over the top of the pan and transfer the slab to a cooling rack. Once the slab has cooled completely, transfer it over the a cutting board. Cut the slab into thirds one way, then turn it 90 degrees and cut it into thirds the other way. This will leave 9 equal bars.

Store the bars in an airtight container for up to 3 days, and enjoy!

Bake Time: 350F for 50-55 minutes
Servings: 9 bars
Total Time: 1 hour 30 minutes
Prep Time: 35 Minutes

Ingredients:

Shortbread Crust:

2 cups all-purpose flour
1 teaspoon salt
12 Tablespoons unsalted butter, softened
3/4 cup granulated sugar
1 teaspoon vanilla extract
3-4 Tablespoons whole milk
1 teaspoon cinnamon
1/2 teaspoon allspice

Blackberry Filling:

12 oz frozen blackberries
2/3 cup granulated sugar
2 Tablespoons corn starch
1/2 teaspoon salt
1 Tablespoon lemon juice

Instructions