Combine the feta cheese, parsley, olive paste and egg whites in a bowl and mix well. Unfold 1 of the pastry sheets on a lightly floured surface, keeping the remaining pastry sheet in the refrigerator. Roll into a 14X16-inch rectangle with a floured rolling pin. Cut crosswise into halves. Spread half the olive mixture over 1 pastry half. Top with the remaining pastry half. Roll gently with a rolling pin to seal the layers together. Cut the pastry crosswise into 1/2 –inch-wide strips. Arrange the strips 1 inch apart on a greased baking sheet, twisting each strip 3 or 4 times. Bake at 400 degrees for 12 to 15 minutes of until puffed and light brown. Remove to a wire rack to cool completely. Repeat the process with the remaining puff pastry and remaining olive mixture.
Serve at room temperature. Store in a tightly covered container. You may substitute a mixture of ½ cup pureed pitted kalamata olives and 1 tablespoon olive oil for the olive paste.