Preheat oven to 400 degrees. Line 9- or 10-inch pie plate with pastry. Combine blueberries, sugar, lemon zest and lemon juice and mix gently. Sprinkle with flour and combine well. Pour into pastry-lined plate and dot top with butter. Roll out top crust and crimp edges. Or make lattice crust by cutting top pastry into strips and placing atop filling, then crimping edges. Brush top crust with heavy cream. Bake about 45-50 minutes, or until filling is bubbling and crust is golden.