Pistachio Lemon Oatmeal Bars
Cinnamon oatmeal crumble bars with pistachios in the oatmeal cookie (bottom and top) filled with tart, smooth lemon curd.
While you might be more accustomed to seeing oatmeal crumble bars with a berry filling, I invite you to give this lemon and pistachio version a try. The cinnamon, pistachio and oat cookie bar along with the crumble on top are delightful on their own, but I’ve added a wild card (but probably wholly expected from this blog tbh) filling: lemon curd.
The result is a bar that sparks joy in the contrast of crunchy bar, with it’s warming spices and delectable tart filling.
Recipe Origins
I was inspired to create these when I saw Sally’s oatmeal lemon crumble bars. Hers is an oat base and a lemon filling that’s more like a key lime pie (or lemon creme). My recipe is a lemon take on my rhubarb oatmeal bars; in lieu of the rhubarb jam I’ve used my beloved lemon curd. I also added pistachios to this cookie base.
Recipe Ingredients
Lemon curd: make half of this recipe or make this microwave/mason jar lemon curd recipe (the latter makes a bit less).
Oats: old fashioned rolled oats – not instant oats.
Butter: unsalted or salted, if using salted you may want to reduce the added salt to the dough.
Cinnamon: ground. If you don’t like lemon and cinnamon together you can skip this.
Sugar: brown, light or dark works.
Pistachios: I buy my pistachios raw and toast them myself. You can also use toasted but you’ll want to toast them a bit first to freshen up the flavor and crunch. If you’d like to make these nut free, omit.
Egg: large, it’s best if it’s at room temperature.
Flour: all purpose flour. A gluten free 1 to 1 substitute would work too.
How to make Pistachio Lemon Oatmeal Bars
Prep
Follow the recipe to make lemon curd, you’ll need half the batch. You can also use my microwave lemon curd recipe too.
Toast the pistachios: spread them on a cookie sheet and depending on whether they are pre-roasted or not, they’ll bake for 5-10 minutes (longer for raw).
Once fragrant and hot, let cool. Then pulse in a food processor until finely ground. Careful not to overgrind these or you’ll make a pistachio paste.
Toast the oats: set them in a large frying pan over medium heat. Cook, tossing frequently until fragrant and hot. Set aside to cool.
Divide: you’ll need to set aside some oats and some pistachios for the topping which is more of a crumble than a cookie base, a quarter cup of oats and a few tablespoons of the pistachios.
Line a square pan: 8×8 or 9×9. If you want thicker bars use the 8 inch pan. Grease the pan then use two overlaying sheets of parchment to line it.
Make the oatmeal dough
Melt the butter then beat in the sugar and flavorings.
Whisk or beat in in the egg.
Stir or beat in the flour and the oats (minus that quarter cup you set aside for the topping).
Stir in the ground pistachios (minus the few tablespoons set aside for the topping).
Press two thirds of the mixture into the bottom of the pan. Use flat hands or a measuring cup to even out the layer and pack it in.
Spread the lemon curd over the oatmeal dough.
Stir or use your hands to mix the remaining dough with the reserved oats and ground pistachios.
Crumble the mixture and sprinkle it over the lemon curd in big clusters.
Bake the bars until golden all over – about thirty minutes.
Make Ahead & Storage Info
The lemon curd portion of the recipe can and should be made at least a day ahead of time or up to two weeks. It keeps well in the fridge for 2 weeks, in an airtight container.
You can cut these the day of baking (or within a few hours) but the curd won’t have set until it’s been in the fridge for at least 4-8 hours.
The bars, once baked, keep best in the fridge. They’ll be good for about 5 days.
Pistachio Lemon Oatmeal Bars Recipe
Pistachio Lemon Oatmeal Bars
Ingredients
- 100g or 1 cup unshelled pistachios divided
- 230g or 2 cups old fashioned rolled oats divided
- 113g or ½ cup unsalted butter
- 200g or 1 cup brown sugar
- ½ tsp fine sea salt
- ½ tsp ground cinnamon
- 1 large egg
- 165g or 1 ¼ cups all purpose flour
- ½ tsp baking soda
- Lemon curd half this recipe
Method
- Have your lemon curd ready and chilled before beginning the cookie dough.
- Preheat the oven to 350 F. Spread the pistachios on a small cookie sheet and toast for 5-7 minutes, until fragrant. Set cool on the counter until completely cool. Grind the pistachios in a food processor until you have fine crumbs (pulse it to ensure it doesn’t turn into a paste!)
- In a large frying pan, add the oats. Set over medium heat on the stove. Warm until hot and fragrant, tossing for even heating. Set aside to cool. Divide into 200g (1 ¾ cups) and 30g (¼ cup); the greater amount is for the bottom of the bar, the lesser will be for the topping.
- Set the butter in a large heat safe bowl and warm until melted (60 seconds in the microwave should do it). Add the brown sugar, salt, and cinnamon, and whisk well to combine.
- Whisk in the egg then switch to a rubber spatula and add the flour and baking soda, stir until smooth. Add the reserved greater amount of oats (200g or 1 ¾ cup) as well as most of the ground pistachios (the remainder will go into the crumble topping) and stir to combine.
- Prepare a square baking pan, 9x9 or 8x8 (the latter will make thicker bars) by greasing it then lining with parchment paper (two overlaying sheets). Have the oven at 350 F for baking.
- Press ⅔ of the oat mixture into the bottom of the pan, it should be flat and even. Pour the lemon curd on top and smooth into an even layer.
- To the remaining oat mixture add the remaining oats (about ¼ cup) and (ground pistachios a few tablespoons). Use your hands to work it together until combined. In small bits, crumble/sprinkle the topping over the lemon curd, spreading it all over and leaving only small gaps.
- Bake the bars until golden all over, for about 25-30 minutes. Let cool completely then transfer to the fridge to chill for a few hours. You can cut them before chilling, but the lemon curd will be a bit messy. Store leftovers in the fridge.
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