Lemon Meringue Bars

1 package pie crust mix
1/4 cup granulated sugar
4 eggs
1 cup granulated sugar
1 1/2 teaspoons grated lemon rind
1/4 cup lemon juice
1 tablespoon all-purpose flour
2 egg whites, at room temperature
1/8 teaspoon cream of tartar
3 tablespoons granulated sugar

Preheat oven to 350 degrees F. Grease a 13 x 9 x 2-inch baking pan.

Blend pie crust mix, the 1/4 cup of sugar and 1 of the eggs in a medium size bowl with a pastry blender. Pat dough gently into prepared baking pan. Bake for 10 minutes. Remove to wire rack, leaving oven on.

Beat the 3 remaining eggs and the 1 cup sugar in a medium size bowl with electric mixer until light and fluffy. Beat in lemon rind and juice and flour; pour mixture over pie crust. Return to oven; bake 15 minutes longer.

Beat egg whites with cream of tartar in a medium size bowl with an electric mixer until frothy. Beat in remaining 3 tablespoons sugar, 1 tablespoon at a time, until meringue forms stiff peaks.

Remove pan from oven. Increase oven temperature to 450 degrees F. Spread meringue mixture over lemon mixture. Return to oven and bake 5 minutes more or until meringue peaks are golden brown. Cool on wire rack. Cut with a wet knife into bars.