Pistachio Rhubarb Shortbread
Two layers of buttery, nutty pistachio shortbread that melts in your mouth is interrupted by a bright tart pop of jammy rhubarb.
I had been reading an article about rhubarb flavor pairings and one of the ingredients listed was pistachios. Y’all know how I feel about pistachios so I came up with these bars: two layers of pistachio shortbread (which is so good I already have some other ideas for what to do with it!) and a purely rhubarb filling, with some pops of lemon in the shortbread, the glaze, and even the jam.
Recipe Origins
This recipe is an adaptation of an older one on the blog, these blueberry rhubarb bars. Made with a shortbread base, a blueberry rhubarb jam, and bits of shortbread on top. I more or less kept the basis of the recipe, but made the filling fully rhubarb (it also makes a smaller batch so there won’t be leftovers) and added ground pistachios to the shortbread.
Recipe Ingredients
Sugar: fine granulated. We’ll use some in the rhubarb jam and some in the shortbread. Rhubarb: fresh. Dice it into one inch pieces. If you have previously frozen some rhubarb and want to use that, thaw it and remove the excess water before using.
Starch: I use tapioca starch but cornstarch works too.
Lemon: we’ll use some juice in the jam, zest in the jam, lemon zest in the pistachio shortbread and some lemon juice in the glaze.
Butter: unsalted, and since this is a shortbread that’s butter forward I’d recommend using a good quality butter with a higher butterfat percentage (83% or higher, from european brands).
Salt: fine sea salt.
Vanilla: this isn’t completely necessary in the shortbread but it does enhance the flavor, it’s needed definitely in the glaze.
Flour: all purpose flour.
Powdered sugar: preferably made with tapioca starch.
Pistachios: it’s easier to use unshelled raw pistachios, which you can roast yourself before baking for the best flavor. You can also shell the pistachios yourself, or buy roasted. If you buy roasted, consider reducing the added salt to the recipe. I’d also toast them for 5 minutes in the oven, at 350 F to freshen up the flavor. Always wait for the pistachios to be cool before adding to the dough!
How to Make Pistachio Rhubarb Shortbread
Make the filling
Chop the rhubarb into 1 inch pieces. Be sure to discard the leaves as they are toxic.
Add the chopped rhubarb, the sugar, lemon, starch and a pinch of salt to a pot.
Stir and set the pot over medium low heat.
Cook, stirring often, until the rhubarb softens and starts to fall apart (some bigger pieces are fine – remember this will also be baked). The remaining liquid will be thick.
Set aside to cool.
Make the shortbread
Toast the nuts: preheat the oven to 350 F and spread the pistachios on a baking sheet. If they are raw, toast them for about 10 minutes until fragrant. If they are roasted, you’ll only need to do around 5 minutes.
Let the pistachios cool completely while you make the dough.
Use a stand mixer and its paddle attachment, or a hand mixer with beaters: whisk together the sugars, salt, lemon zest, and flour.
Add the butter and vanilla and beat to combine.
Grind the nuts until they are finely ground, using a food processor. Add them to the dough and beat to combine.
Assemble and bake
Preheat the oven to 350 F. You’ll want a nine inch metal baking pan (it can be circle for wedges as pictured, or square for more of a bar shape). Grease it with oil or butter then lay a sheet of parchment to fit in the bottom and sides. If the pan is round, press it in and don’t worry about the creasing. If the pan is square, you can cut to sheets of parchment to fit and lay them over each other to cover all sides of the pan.
Press around two thirds of the pistachio dough into the bottom of the pan. Flatten it so it’s in one even layer.
Spread the rhubarb filling over the first layer.
Use your fingers to gather the dough into little bits and sprinkle them on top of the rhubarb jam. We want some of the rhubarb exposed so don’t cover it completely. See the photos for reference.
Bake the shortbread for about 30 minutes; you’re looking for the edges and top to have turned golden.
Let cool completely before glazing.
Recipe Notes
- Because it’s got a wet filling, the shortbread will become softer after a few days. If you wish to keep it on the crispy side, store it in the fridge in an airtight container.
- If you’d like to substitute the pistachios with another nut, I’d use pecans or walnuts. Hazelnuts could work too; bear in mind some nuts are more ‘buttery’ than others so you may want a few extra tablespoons of flour to the dough if you feel it too wet.
- You can make the filling ahead of time if you like; once cool transfer it to an airtight container and store in the fridge. It should be good to use for a little over a week.
Lemon Pistachio Rhubarb Shortbread Recipe
Pistachio Rhubarb Shortbread
Ingredients
Lemon Rhubarb Filling
- 70g or ⅓ cup fine granulated sugar
- 260g fresh rhubarb chopped into 1 inch pieces
- 2 teaspoons tapioca starch or cornstarch
- Juice of half a lemon about a tablespoon
- Zest of 1 lemon
Lemon Pistachio Shortbread
- 226g or 1 cup unsalted butter at room temperature
- ½ tsp fine sea salt
- 1 teaspoon pure vanilla extract
- Zest of 1-2 lemons
- 60g or ⅓ cup powdered sugar
- 2 tablespoons sugar
- 260g or 2 cups all purpose flour
- 150g or 1 heaping cup pistachios
Lemon Vanilla Glaze
- 90g or ¾ cup powdered sugar
- 2 tablespoons freshly squeezed lemon juice
- Dash vanilla paste or extract
- Pinch fine sea salt
Method
Make the rhubarb filling:
- Slice off the leaves and bottom stem of the rhubarb. Cut into 1 inch pieces.
- Set all the ingredients for the filling in a pot over medium low heat. Cook, stirring frequently, until the rhubarb softens and starts to fall apart. The surrounding liquid will become thick, about 15-20 minutes. Leave to cool.
Make the pistachio shortbread:
- Preheat the oven to 350 F. Spread the pistachios on a baking tray and roast them in the oven until fragrant, shaking the pan after 5 minutes. Don’t bake any longer than 10 minutes. Let cool.
- Set the sugars, flour, salt, and lemon zest in the bowl of a stand mixer. Affix the paddle attachment and whisk to combine.
- Add the butter and beat until creamed. The pistachios should be completely cool now, set them in a food processor and process until finely ground. Add to the bowl with the shortbread dough and beat to just combine.
- Grease a 9 inch round cake pan (square works too) and line it with parchment paper. For a round pan, just press the parchment in creasing it as needed to make it fit. You can use metal clips to hold it in place.
- Take about ⅔ of the pistachio shortbread dough and press it into the bottom of the pan. Over this, spread the cooled rhubarb filling. With the remainder of the shortbread dough, sprinkle it in little bits all over the rhubarb.
- Bake at 350 F until the edges and top are golden, for about 30 minutes. Let cool completely before glazing.
- To make the glaze: whisk all the ingredients together then drizzle the glaze over the shortbread bars.
Did you make this recipe?
Share & tag me on instagram @buttermilkbysam
