Preheat oven to 400° F. and butter an 8-inch (1 1/2-quart) glass pie plate.
In a bowl toss together blueberries, zest, sugar, lemon juice, and cornstarch until combined well and transfer to pie plate.
Into another bowl sift together flour, baking powder, cardamom, and a pinch salt. Add cream and stir until mixture just forms a dough. Drop dough in 5 mounds on blueberry mixture and bake in middle of oven until biscuits are golden and cooked through, about 25 minutes.
