3/4 cup granulated sugar, use slightly less if the berries are very sweet
1/4 teaspoon salt
2 teaspoons finely shredded lemon peel
1 teaspoon grated fresh ginger
3 tablespoons lemon juice
2 tablespoons cornstarch
1 tablespoon whipping cream
1 tablespoon coarse sugar or granulated sugar
Whipped cream or vanilla ice cream
Preheat oven to 375°F. For biscuits, place walnuts in a food processor, pulse several times until roughly chopped. Add flour, brown sugar, baking powder, baking soda, and the 1/2 teaspoon salt. Pulse several times until combined. Add butter, pulse again until butter pieces are no larger than small peas.
Transfer the flour mixture to a large bowl. Add buttermilk, stirring with a fork until the dough comes together. Transfer dough to a lightly floured surface; knead two or three times to bring dough together. Press dough into a rectangle or circle 1/2-inch thick. Using a knife or 2 1/2-inch fluted round cutter, cut the dough into eight squares or rounds, re-rolling the scraps as necessary.
In a 3-quart rectangular baking dish combine berries. In a small bowl combine the 3/4 cup granulated sugar and the 1/4 teaspoon salt. Mix lemon peel and ginger into sugar mixture, pour sugar mixture over berries; gently toss with hands to combine. Combine lemon juice and cornstarch. Add cornstarch mixture to berry mixture; toss.
Brush tops of biscuits with whipping cream; sprinkle with the coarse sugar. Arrange biscuits on top of fruits. Bake in preheated oven for 25 minutes. Loosely cover baking dish with foil; bake for 10 to 20 minutes or more or until bubbly around the edges. Transfer baking dish to a wire rack; remove foil. Cool on wire rack for at least 20 minutes before serving.
To serve, spoon each biscuit and berry mixture into eight serving bowls; top with whipped cream or vanilla ice cream if desired.