Plum Crumble Bars aka "The PLUMBLE"

This recipe began as a simple French recipe called Prune Plum Tart that I inherited from my grandmother. I loved it even then, but each September I'd find myself jotting little notes in the margins: try brown sugar in the crumble instead of white, add an egg yolk to the crust for more structure, increase the salt. It's turned into the slowest recipe development project of all time, because the bars were always delicious, the season for Italian prune plums is short, and the recipe was just for me, anyway.

Over the years, the tweaks piled up. The crust became (a little bit) sturdier, the crumble more layered, the fruit juices sweetened and thickened. Last year, friends insisted I stop adjusting. "It's perfect," they told me. And maybe it is, but tinkering has become part of the tradition. It was everything I could do to leave the recipe as is this year, but then it came out of the oven and I was so happy with the end result. I think I'm finally ready to let this one stand. 

The one constant in the recipe has always been the fruit. These bars are designed to let the plums shine, with just enough spice in the topping to add warmth and complexity. I use Burlap & Barrel cinnamon and cardamom, both so vibrant that a little goes a long way. If your spices are more basic, you may want to increase the amounts.

The resulting tart is jammy and buttery, like a pie distilled into its most essential parts. A couple of tips: the crust, essentially a sablé, will soften quickly if the fruit is wet, so if your fruit is especially juicy, increase the tapioca slightly. And always bake until the juices at the centre are thickened and syrupy; that's when you know they'll set properly and give you bars that slice neatly and last a little longer.

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Plum Crumble Bars aka “The Plumble”

Makes 16 squares

Crust
½ cup (113 g) unsalted butter, cut into pieces
1 cup (135 g) all-purpose flour
3 tbsp (40 g) granulated sugar
½ tsp Diamond Crystal kosher salt
1 egg yolk

Filling
454 g small firm-ripe blue prune plums (about 15)
3 tbsp (40 g) granulated sugar
4 tsp tapioca starch

Topping
3 tbsp (38 g) light brown sugar
¼ cup (34 g) all-purpose flour
2 tbsp (30 g) unsalted butter
¼ tsp Diamond Crystal kosher salt
¼ tsp Burlap & Barrel Royal cinnamon
¼ tsp Burlap & Barrel Cloud Forest cardamom
3 tbsp (20 g) finely chopped toasted walnuts

Method

1. Preheat oven to 350°F. Line an 8-inch square pan with parchment paper.

2. Combine butter, flour, sugar, and salt in a food processor or bowl. Pulse or rub with fingers until butter is the size of peas. Add egg yolk and mix until dough just starts to clump. Press evenly into prepared pan. Bake 22–25 minutes, until lightly golden all over. Cool slightly.

3. Halve plums lengthwise and remove pits (if you have larger plums you can quarter them). Toss with sugar and tapioca; let sit 20 minutes until juicy and all powdery bits are moistened.

4. For the topping, combine brown sugar, flour, butter, salt, cinnamon, and cardamom until crumbly. Add walnuts, squeezing crumble with your fingers to get a mix of big and small pieces.

5. Lay plums evenly over crust (a checkerboard of plums skin side up and down fits neatly if you like a pattern). Scrape any juices over top. Sprinkle with topping. Bake 1 hour to 1 hour 10 minutes, or until plum juices have bubbled and thickened and the topping is golden. Cool before cutting into squares.

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This recipe always feels like the true start of baking season. It feels good to turn the oven on again, and to fill the house with the scent of butter, fruit, and spice. Fresh, vibrant spices from Burlap & Barrel, Diaspora Co and Épices de Cru make all the difference here. 

[Stock up for fall baking →]