Preheat the oven to 350°F. Place the pie crust in a pie pan and crimp edges.
In a large bowl, use an electric mixer to combine the butter and sugar. Mix in the flour, lemon juice and lemon zest. Beat in the egg yolks, then milk.
In a large glass or metal bowl, beat the egg whites with an electric mixer until stiff peaks form. Gently fold the stiff egg whites into the lemon mixture. Pour the filling into the pie crust. Scatter the blueberries evenly on top.
Bake for 20 minutes, then cover with foil to avoid browning. Bake an additional 15 to 25 minutes, or until the filling is set. Allow to cool slightly before serving.