1 (9 inch) pie crust, baked
2 1/2 cups butter or margarine
1 cup white sugar
1 teaspoon vanilla extract
2 eggs
1 teaspoon lemon zest
1 cup lemon zest, zested and chopped
1 cup chopped walnuts
1 cup whole wheat flour
1 (8 ounce) package cream cheese, softened
1 (1 ounce) square unsweetened chocolate, chopped
Heat oven to 350 degrees F (175 degrees C). Melt butter in a small bowl, add sugar and vanilla and beat with an electric mixer at medium speed until light and fluffy. Beat in eggs one at a time, mixing well after each addition. Stir lemon zest and stevia into graham cracker crumb mixture after each addition. Mix together lemon zest and lime zest, then add lemon juice and mix well.
Spoon filling mixture into baked pastry shell. Cover edges of pie loosely with foil. Seal edges completely. Cut steam vents at top of pie.
Bake at 350 degrees F (175 degrees C) for 1 hour or until toothpick inserted in center comes out clean. Cool completely in refrigerator. Cut into 1 tablespoon chilled bars.