Mix the flour, sugar, butter, zest, lemon juice, egg yolks, coconut (optional), and milk together in a bowl.
In a separate bowl, beat egg whites untill very stiff peaks form. Fold lemon mixture into the egg whites. Pour combined mixture into unbaked pie crust.
Loosely cover the top of the pie with tin foil to prevent over browning. Bake in 450 degree oven for 10 minutes, then reduce heat to 350 degrees and bake for 30 minutes, or until a knife inserted into the center of pie comes out clean.
Let the pie cool to room temperature, then top with whipped cream and serve.