Preheat oven to 375 degrees with racks in middle and bottom. Line a baking sheet with aluminum foil and place on bottom rack to catch any juices that might bubble over. Stir together berries, sugar, cornstarch, salt, and lemon juice. Transfer to a 2 1/2-quart baking dish.
Whisk together flour, sugar, baking powder and salt. Cut in butter until the largest pieces are the size of small peas. Add cream, and use a fork to incorporate, stirring until a soft sticky dough forms. Dollop dough over filling, dividing evenly into 9 pieces. Brush with cream and sprinkle with sugar.
Bake until biscuits are golden brown and filling is bubbling in the center, about 1 hour and 10 minutes. Cool at least 1 hour before serving. Serve warm or room temperature with a scoop of ice cream or drizzled with heavy cream, if desired.