Blueberry, Oat and Almond Crumb Bars

These blueberry crumb bars with oats and almonds are a perfect bake sale recipe and our favorite way to use up summer blueberries.

Blueberry, Oat and Almond Crumb Bars

A few years ago while we still lived in Brooklyn, Matt and I belonged to a CSA. If you’re not familiar with it, CSA stands for ‘community supported agriculture’. The gist of it is that you pay in advance for a ‘share’ of what the farm produces.

It helps the farmers because they get money in advance so they can better finance their year, and the customer gets a weekly (or bi-weekly) supply of the freshest, just-off-the-farm produce.

Of course, by investing in the farm’s potential, you also share some of the risks. If there’s a flood, or a blight, or a generally low yield of crop that season, you might not get as many tomatoes as you’d like and you just have to channel your inner hippie and roll with it, man. What’s more likely though, is that you’ll end up with way more of a certain fruit or vegetable than you know what to do with. And that’s when you have to get creative.
Blueberry, Oat and Almond Crumb Bars

There was one week during our CSA that we received more blueberries than I had ever seen in my life outside of a grocery store. It was a huge box of them. We had them on yogurt and on cereal. I made blueberry syrup. Matt made a crumble. And still we had more. And then I made Blueberry Oat Bars with the rest and kicked myself for not making them sooner because they were the best thing ever. They’re not so sweet that you’d feel guilty having one for breakfast but they have that crunchy, nutty topping that is such a treat.

Now we grow too many of our own vegetables to make joining a CSA worth it (one day Matt will post a garden update and we’ll show you, WILL WE SHOW YOU, but we did a straw bale garden this year and it is amazing, honest). We’re not growing blueberries (yet), so we bought a couple of pints fresh and also used some frozen.

Blueberry, Oat and Almond Crumb Bars

I added almonds to the topping because I love that combination. Also, a little touch of lime juice and zest really perks up the berries.

Blueberry, Oat and Almond Crumb Bars
So patriotic!

Because we made these for a July 4th party, we served them with some Maple Whipped Mascarpone and Macerated Strawberries (for a little red, white and blue action). Look for those recipes below in Nerd Tips.

Quick aside: I’m not much of a holiday person but, Matt being an Englishman, July 4th is my opportunity to dance around gloating about #winning and #independence and who kicked whose #ass. And then he makes me a nice delicious cup of tea and a Hob Nob and smirks for some weird reason.

Nerd Tips:
  • To make Macerated Strawberries; slice berries and place in a bowl. Spoon over a bit of sugar (I usually start with  teaspoon or so and taste). When berries are sweet enough, toss them gently and let them sit for a few minutes. They’ll get nice and juicy.
  • To make Maple Whipped Mascarpone: Place 8 oz of mascarpone into a bowl. With a whisk, whip in 2 tablespoons of maple syrup until light and fluffy. If it’s too thick, stir in a couple of tablespoons of milk or cream.
  • You could use lemon instead of lime. I just like the slightly floral scent lime has.
  • Walnuts or pecans would also work in the topping.
  • These are a bit too goopy to cut while warm so make sure to chill them first.
  • Demerara is a type of cane sugar with a fairly large grain and a pretty, pale amber color. It has great texture and a pleasant toffee flavor. A little sprinkling on top gives the crumble extra crunch but you can leave it out or use white sugar if you want.
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Blueberry, Oat and Almond Crumb Bars

Prep Time20 minutes
Cook Time45 minutes
Total Time1 hour 5 minutes
Servings: 24 bars


  • For the crust and crumble:
  • 1/2 cup + 2 tablespoons white sugar 125g
  • 1/2 cup packed light brown sugar 90g
  • 1 teaspoon baking powder 3.8g
  • 1/4 teaspoon fine sea salt or table salt
  • 2 cups all-purpose flour 240g
  • 3/4 cup old-fashioned whole-rolled oats don't use quick-cook or instant (60g)
  • 1 cup cold unsalted butter 2 sticks or 8 ounces (230g)
  • 1 large egg
  • 1 cup flaked almonds added at the end (170g)
  • 2 tablespoons Demerara sugar optional (24g)
  • For the blueberry filling:
  • 4 cups blueberries fresh, frozen or a mix (if frozen, no need to defrost) (1.5 lbs / .68k)
  • Zest and juice of one lime or lemon (about 1 1/2 tablespoons juice)
  • 3/4 cup white sugar 144g
  • 4 teaspoons cornstarch 6.5g


  • Preheat the oven to 375º F / 190º C). Line a 9×13 inch pan with foil or parchment.
  • Cut the cold butter into 1/2 inch cubes and set aside. In a medium bowl, stir together white and brown sugars, flour, oats, salt and baking powder. Cut in the butter and egg using a fork or a pastry cutter, or even your fingers. Dough should have a rough, sandy texture. Move half the dough into the lined pan and press into the bottom using your fingers.
  • In another bowl, gently stir together the blueberries, sugar, cornstarch and lime juice and zest until just combined. Sprinkle the blueberry mixture over the crust. Add almonds to the remaining dough and give it a quick stir, then crumble over the berry layer. I like to squeeze a few bits together in my fingers to ensure some nice big crumbs. Sprinkle Demerara sugar evenly over the top (if you’re using it).
  • Bake for 45-55 minutes, or until top is a light golden brown. Set pan on a wire rack and let it cool completely before cutting into squares (refrigerated bars cut even better). Bars will keep airtight in the fridge for up to 10 days, or in the freezer for up to 6 months.
Tried this recipe?Mention @NerdsWithKnives or tag #nerdswithknives!

6 thoughts on “Blueberry, Oat and Almond Crumb Bars”

  1. HEY OP! I found this recipe on reddit! I made this for the 4th of July and it was a huuuuge success and a hit! So thanks for that. It was absolutely delicious! Looking forward to future recipes.

  2. I found you from Reddit and had this recipe bookmarked for a while. Just made it last night, as-is (but no sugar or almond on top) and I really enjoyed the flavor of the lime with the blueberries. However, I did think the sweet factor was somewhat single-note. If I make it again, I’ll probably try reducing the sugar and perhaps adding some bananas for some more depth. I may also swap out half the butter for applesauce because these were super rich (and calorie dense).

    Thanks for the interesting recipe!

  3. I realize this is an older post, but have to say these are amazing! I made as written (using lemon juice) with the addition of a splash of vanilla to the blueberry mix. I used frozen berries and was worried that the filling would get soupy, but the corn starch balanced it perfect. The crust was buttery and golden. My office devoured them!

    • Thanks so much Melissa! I’m so glad everyone liked it 🙂 Would you mind giving the recipe a star rating? It helps other people find it when they’re searching for options.


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