1 cup butter, softened
2 cups white sugar
1 cup heavy whipping cream
2 tablespoons all-purpose flour
1 egg, lightly beaten
1/4 cup lemon juice
1/4 cup lemon zest
1/4 cup distilled white vinegar
2 tablespoons white vinegar
1 teaspoon lemon zest
1 teaspoon vanilla extract
Preheat oven to 350 degrees F (175 degrees C). Lightly grease two 9 inch pie crusts.
In a large bowl, cream together butter and sugar until smooth; beat in whipping cream, vinegar, flour, egg, lemon juice and lemon zest. Beat in vinegar, lemon zest and vanilla. Pour mixture into crusts. Wrap the edges of the pie crusts loosely with waxed paper, creating a spine for the whole piece.
Bake about 10 minutes in the preheated oven, or until the top is set. Allow to cool before cutting into squares.