Blackberry Crumble Jam Bars with Oat Streusel

Blackberry Jam Bars cut into squares

Sweet and incredibly delicious, these blackberry jam bars, or crumble bars, are made even more perfect with an easy oat streusel.

So perfect, in fact, you’ll find yourself making them all summer long. Maybe even all year long.

Here’s why…

Blackberry Crumble Jam Bars

These crumble jam bars have a sturdy, oatmeal-cookie like base and a streusel like topping made from the same dough. In between these sweet and delicious layers is a gooey layer of jam.

We used blackberry jam, because I’m craving all things blackberry this year, but any jam you love would be yummy. I love the contrast of a darker-hued jam; like plum, blueberry, black raspberry, or even fig would be beautiful too. 

The Jam Bars Crust

The crust is sturdy and oh-so-delicious and is made with the usual:

• oats
• flour
• brown sugar
• butter

The Jam Bars Filling

The filling couldn’t be easier. Much like my favorite afternoon tea jam tarts, the filling is simply a fruit jam of your choosing. As I mentioned before, I love a darker-hued jam, but anything works great. 

If the jam is tightly gelled, warm in the microwave for a few seconds to make it easier to spread. 

Blackberry Jam Bars on a White Background

What I Love About These Bars

• Um… easy, easy, easy.

• A cookie-like crust that holds up well to cutting.

• Perfect for packable lunches … and yes, picnics too!

• Or making for church potlucks, block parties, office parties… or the friend who needs sweet encouragement.

Squares of Blackberry Crumble Jam Bars


Blackberry Crumble Jam Bars with Oat Streusel

thumbnail: blackberry crumble bars

These Blackberry Crumble Jam Bars are my favorite summer dessert. Like, the taste of the season, in every bite. Soft, buttery, and oh-so-yummy!

  • Author: Stephanie Wilson
  • Prep Time: 10 minutes
  • Cook Time: 35
  • Total Time: 45 minutes
  • Yield: 16 squares 1x
  • Category: Dessert
  • Method: Bake


3 cups old fashioned oats
3 cups all-purpose flour
11/2 cup packed brown sugar
1 teaspoon baking powder
12 tablespoons butter, melted (1-1/2 cups)
1/2 teaspoon salt
13 ounce jar blackberry jam (heaping cup)


Preheat the oven to 350 degrees and line a 9×13 inch baking pan with parchment paper. Set aside.

Making the Crust: Mix the oats, flour, brown sugar, baking powder, melted butter, and salt together until a crumble-like mixture emerges. Press two thirds of the crumble into the bottom of the prepared baking pan. Bake for 10 minutes.

Baking the Jam Bars: Remove the crust from the oven and spread the jam over the top. If necessary, warm the jam in the microwave until it is spreadable. Sprinkle the remaining 1/3 streusel over the top of the jam layer; bake for another 25-30 minutes.

Cooling: Remove the bars from the oven and cool completely before cutting. Because I can be a tad impatient — and my guys will devour them too soon, I like to refrigerate the bars until they become solid enough to cut. But… if you’re like me and can’t wait, sometimes, they’re kind of good warm too. Add some melty vanilla ice cream for an extra special treat. Otherwise, cut into 9 to 16 bars when cool and firm.

Keywords: Blackberry Crumble Jam Bars with Oat Streusel, Blackberry Crumble Bars, Jam Bars

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