Yield: 8 servings
For pastry stars:
2 sheets frozen puff pastry, thawed
An egg wash made by whisking:
1 large egg yolk
1 tablespoon water
For berry mixture:
1/3 cup water
3 tablespoons fresh lemon juice
3 1/2 tablespoons cornstarch
5 cups fresh blueberries (about 5 half-pints)
5 cups fresh raspberries (about 4 half-pints)
2 1/2 to 2 3/4 cups sugar, or to taste
Preheat oven to 400 degrees.
Make pastry stars: On a lightly floured surface with a lightly floured rolling pin roll out each puff pastry sheet into a 14x13-inch rectangle. With 1 or more star-shaped cutters cut out 24 pastry stars. Divide pastry stars between 2 baking sheets, arranging in one layer, and freeze 5 minutes.
Remove baking sheets from freezer. Brush top of each pastry star lightly with some egg wash (be careful not to drip down edges of pastry) and bake in middle and lower third of oven about 5 minutes. Alternate baking sheets and bake 5 to 10 minutes more, oruntil pastry stars are puffed and golden brown. Transfer pastry stars to a rack and cool completely. Pastry stars may be made 2 days ahead and kept in a sealed plastic bag at room temperature. Yield: 24 stars
Make berry mixture: In a large bowl whisk together water, lemon juice, and cornstarch until combined well. Add berries and sugar, tossing gently to combine well. Divide berry mixture evenly among eight 1 1/2-cup shallow ramekins or baking dishes and put in 2 shallow baking pans. Bake berries in middle and lower thirds of oven 25 minutes and cool slightly.
To assemble cobblers: Top each serving decoratively with pastry stars and a scoop of ice cream. Serve hot or warm.