Heat oven to 375° F. In a shallow 1 1/2-quart baking dish or a 9-inch deep-dish pie plate, toss the blueberries, 1/3 cup sugar, and 1 tablespoon flour.
In a medium bowl, combine the baking powder, salt, lemon zest, and the remaining flour and sugar.
Add the butter and blend with your fingers or 2 knives until coarse crumbs form. Add 3/4 cup plus 2 tablespoons cream and mix until a shaggy dough forms.
Drop mounds of dough over the blueberry mixture. Bake until the berries are bubbling and the top is golden, 35 to 40 minutes. Serve with the remaining cream for drizzling, if desired.