Preheat the oven to 400 degrees F and coat an 8 x 8-inch square or 2-quart baking dish with nonstick cooking spray.

Make the Filling: Combine sugar, cornstarch, water, and lemon juice in a large saucepan. Stir in the blueberries. Cook and stir until thickened and bubbly. Transfer the blueberry mixture to the prepared baking dish and keep the filling hot.

Make the Topping: Combine the flour, sugar, baking powder, and salt in a medium-size bowl. Cut in the cold, diced butter until the mixture resembles fine crumbs. Fold in the cream and vanilla just until combined.

Drop spoonfuls of the topping onto the hot blueberry mixture.

Bake the cobbler until the topping is golden and the filling is bubbling; 20 to 25 minutes. Let cool for 20 minutes before serving warm with whipped cream or ice cream.