Why It Works
- A handful of raspberries rounds out the sharp and often bitter astringency of blackberries.
- With truly sour fruit, a pinch of baking soda will neutralize excess acidity.
- Just a touch of cinnamon amplifies the natural flavor of blackberries.
It's hard to beat warm and jammy blackberries under a light and crispy biscuit crust, but with a few simple tricks you can make the most of your fruit (whether picked from a local farm or just your local supermarket). A small portion of raspberries will round out the flavor of sour or underripe blackberries, but with perfect fruit there's no need for a blend.
- For the Filling:
- 7 ounces sugar (about 1 cup; 200g)
- 1 1/4 ounces (about 1/3 cup; 35g) tapioca starch (see note)
- 1/4 teaspoon (1g) Diamond Crystal kosher salt; for table salt, use about half as much by volume or the same weight
- 1/4 teaspoon ground cinnamon
- 1/8 teaspoon baking soda
- 32 ounces fresh blackberries (about 5 1/2 cups; 910g)
- 8 ounces (about 1 1/3 cups; 225g) fresh raspberries (see note)
- For the Topping:
- 4 1/2 ounces all-purpose flour (about 1 cup, spooned; 125g)
- 1/2 ounce sugar (about 1 tablespoon; 15g)
- 1 1/2 teaspoons baking powder
- 3/4 teaspoons (3g) Diamond Crystal kosher salt; for table salt, use about half as much by volume or the same weight
- 4 ounces cold unsalted butter, cut into 1/2-inch cubes (about 8 tablespoons; 110g)
- 4 ounces cultured lowfat buttermilk or kefir, cold (about 1/2 cup; 110g)
- To Serve:
- Brown sugar or lemon whipped cream (optional)
For the Filling: Adjust oven rack to lower middle position and preheat to 400°F (205°C). In a large bowl, whisk together sugar, tapioca starch, salt, cinnamon, and baking soda until well combined. Add berries and toss to coat. Scrape into a 7- by 11-inch glass, ceramic, or stoneware baking dish (do not use metal) and set aside while you prepare the topping.
For the Topping: In a medium bowl, whisk together flour, sugar, baking powder, and salt. Add butter and toss to break up the pieces, then smash each one flat between your fingertips. Continue smashing and rubbing until butter is broken up into small pieces like cereal flakes. Stir in buttermilk with a flexible spatula, then drop the thick dough in 1-tablespoon portions over the prepared dish of fruit. If you like, sprinkle with additional sugar for crispier tops.
Place on a foil-lined half-sheet pan and bake until the biscuits are golden brown and the fruit is bubbling hot in very center, about 1 hour. Cool at least an hour before serving, to allow the filling to thicken (while piping hot, it will be runny and thin). Covered in foil, leftovers will keep 2 or 3 days at room temperature.
Flexible spatula, 7- by 11-inch baking dish, half sheet pan
Due to disparate sourcing practices, tapioca starch manufactured in Asia may be derived from plants other than cassava, which have different gelling properties. Look for products that mention cassava by name on the packaging, such as Bob's Red Mill. If you don't have raspberries, you can substitute them with more blackberries.