Sour cream blackberry bars

Rustic fruit bresserts, always and forever

I realized this week that I hadn’t made a fruit crumb bar yet this summer — how uncharacteristic of me, a great lover and proponent of the RFB (that’s Rustic Fruit Bressert, aka an easy, not-too-sweet fruity thing that can double as breakfast or dessert). As it’s already the second half of August, clearly that needed to be rectified stat.

I love making bars. Thanks to the support of the pan, they’re forgiving, adapatable, and portable. They also feel like less work than either cookies or pie (their closest baking world cousins, IMO), but are just as delicious. As is the case with most of my RFB’s (or let’s be honest, the majority of my baking), this version was very much driven by what was lurking in the fridge and pantry. This time it was half a tub of sour cream, a glut of blackberries and boysenberries (our bushes are showing off this summer; I can’t keep up!), poppyseeds, and spelt and oat flours.

I have made similar bars with many different flour varieties, so you can feel confident swapping these whole grain flours out for whatever you have. Rye, barley, buckwheat, standard whole wheat, einkorn — any of these should work nicely. While using 100% all purpose flour will work in a pinch, whole grains bring flavor and heartiness — I encourage you to use them if possible.

Other bar desserts:

• Coffee date squares

• Brownies with feuilletine crunch

• Gooseberry cheesecake squares

• Brown butter carmelitas

• No-bake chocolate mousse bars

• Sourdough discard jammy fruit bars

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Sour cream blackberry bars

Makes one 9”x9” pan

Ingredients:

For the crust and topping:

• 125g all purpose flour

• 65g spelt flour

• 60g oat flour

• 50g granulated sugar

• 50g light brown sugar 

• 4g (1 tsp) kosher salt (Diamond Crystal)

• 1/4 tsp baking soda

• 20g poppy seeds

• 170g unsalted butter, cold and cubed

• 30g full-fat sour cream

• 1/2 tsp vanilla

• 30g rolled oats

• Coarse sugar, for sprinkling

For the filling:

• 200g full-fat sour cream

• 65g granulated sugar

• 1 large egg

• 2 tsp freshly squeezed lemon juice

• 8g (1 Tbsp) all-purpose flour

• 2g (1/2 tsp) kosher salt (Diamond Crystal)

• 1 tsp vanilla extract

• 340g fresh blackberries, halved if large

Method:

1. Preheat the oven to 350°F with a rack in the middle. Line a 9 x 9-inch pan with two long criss-crossed pieces of parchment, leaving a couple of inches of overhang on all sides — secure with metal bulldog clips if desired. (This will make it easy to remove the bars later.) Lightly grease the parchment.

2. In the bowl of a food processor, combine the flours, sugars, salt, baking soda, and poppy seeds. Pulse to combine. Scatter the cold, cubed butter over the top. Process in short pulses until no large pieces of butter remain and the mixture resembles coarse cornmeal. Add the sour cream and vanilla and pulse until the mixture starts clumping together.

3. Transfer about a third (~190g) of the mixture to a separate bowl. Add the rolled oats and use your fingertips to pinch in, forming a clumpy streusel. Refrigerate until needed.

4. Transfer the remaining two-thirds of the mixture to the prepared pan. Use your fingers or the bottom of a small glass or measuring cup to press the crumbs evenly into the bottom of the pan. Prick all over with a fork. Bake for about 15-20 minutes, or until set. Transfer to a wire rack while you prepare the filling (no need to let it cool completely).

5. To make the filling, whisk together all filling ingredients except blackberries until smooth. Fold in the blackberries. Pour filling over par-baked crust and spread out evenly, then top with the reserved streusel mixture. Sprinkle generously with coarse sugar.

6. Bake until the crumb topping and custard are set (a toothpick inserted into the center should come out clean), about 30 minutes. Cool completely on a wire rack, then chill for at least an hour in the refrigerator before slicing. Refrigerate leftover bars in an airtight container for up to 5 days; serve cold or at cool room temperature.