Good question, Connee! Beating the egg whites to the proper stiffness, baking the meringue at the proper temperature and for the proper amount of time, and making sure the filling is hot when the meringue is spread over it are all important factors.
Lemon Meringue Pie
1 recipe Baked Pastry Shell
2 cups sugar
1/3 cup cornstarch
2 teaspoons finely shredded lemon peel (optional)
1 cup water
3/4 cup lemon juice
1/3 cup butter, cut up
1 recipe Five Egg White Meringue
1. Prepare Baked Pastry Shell; set aside. Separate egg yolks from whites. Set aside yolks for filling and whites for Five Egg White Meringue.
2. Preheat oven to 325°F. For filling, in a medium saucepan stir together sugar and cornstarch. Stir in lemon peel (if desired), the water, and lemon juice. Cook and stir over medium heat until thickened and bubbly. Remove from heat.
3. Lightly beat egg yolks with a fork. Gradually stir half of the hot lemon mixture into the yolks. Return egg yolk mixture to saucepan. Bring to a gentle boil; reduce heat. Cook and stir for 2 minutes more. Remove from heat. Stir in butter pieces until melted. Cover filling and keep warm.
4. Prepare Five Egg White Meringue. Pour warm filling into Baked Pastry Shell. Immediately spread meringue over filling; seal to edge of pastry. Using the back of a spoon, add high peaks to the meringue. Bake in the preheated oven for 30 minutes. Cool on a wire rack for 1 hour. Chill for 5 to 6 hours before serving; cover for longer storage.
Five Egg White Meringue
5 egg whites
1 teaspoon vanilla
1/2 teaspoon cream of tartar
1 cup sugar
1. Allow egg whites to stand at room temperature for 30 minutes. In a large mixing bowl combine egg whites, vanilla, and cream of tartar. Beat with an electric mixer on medium speed about 6 minutes or until soft peaks form.
2. Gradually add sugar, 1 tablespoon at a time, beating on high speed about 5 minutes more or until mixture forms stiff, glossy peaks (tips stand straight) and sugar dissolves (rub a small amount between two fingers; it should feel completely smooth).
3. Immediately spread meringue over hot pie filling, carefully sealing to edge of pastry to prevent shrinkage. Bake as directed in recipes.
Baked Pastry Shell
1-1/2 cups all-purpose flour
1/2 teaspoon salt
1/4 cup shortening
1/4 cup butter, cut into pieces, or shortening
1/4 to 1/3 cup cold water
1. In a medium bowl stir together flour and salt. Using a pastry blender, cut in shortening and butter until pieces are pea size (see photo 1, below).
2. Sprinkle 1 tablespoon of the water over part of the flour mixture; toss with a fork. Push moistened pastry to side of bowl. Repeat moistening flour mixture, using 1 tablespoon of the water at a time, until flour mixture is moistened. Gather flour mixture into a ball, kneading gently until it holds together.
3. On a lightly floured surface, use your hands to slightly flatten pastry. Roll pastry from center to edges into a circle about 12 inches in diameter (see photo 2, below).
4. Wrap pastry circle around the rolling pin. Unroll into a 9-inch pie plate (see photo 3, below). Ease pastry into pie plate without stretching it.
5. Trim pastry to 1/2 inch beyond edge of pie plate. Fold under extra pastry. prick bottom and sides of pastry with a fork. Line pastry with a double thickness of foil. Bake in a 450°F oven for 8 minutes. Remove foil. Bake 6 to 8 minutes more or until crust is golden. Cool on a wire rack.