1Preheat oven to 325°F. Whisk all the filling ingredients together until smooth; pour into the pie shell and bake for 1 hour, until set but still wobbly in the middle. Cool completely.
2When you're ready to finish the pie (it can be chilled for up to a day), preheat the oven to 400°F. Beat the egg whites with an electric mixer until foamy; gradually add the sugar and continue to beat until the mixture forms stiff peaks. Mound on top of the pie and swirl thickly with a spoon.
3 Bake for about 10 minutes, or just until the meringue turns golden.