FOR THE FILLING:

Preheat oven to 375 degrees F.

Generously butter 9-inch pie plate. Combine blueberries with sugar, flour and lemon juice in medium bowl. Transfer to prepared pan. Bake until berries bubble thickly in center, about 1 hour. Cool completely.

FOR THE TOPPING:

Combine flour, brown sugar, baking powder and salt in food processor. Pulse to blend. Add butter and hazelnuts and blend until mixture resembles coarse meal. Pulse in cream, mixture will form ball. Pat dough out between two sheets of plastic wrap to 9-inch round. Remove 1 sheet plastic wrap and invert dough evenly onto blueberries in dish. Crimp edges decoratively with fork. Bake until topping is golden brown, about 30 minutes. Cool until warm. Sift powdered sugar over grunt and serve with heavy cream or vanilla ice cream.