Beat egg whites until they begin to hold a soft peak. Gradually add Splenda® and continue beating until egg whites are stiff. Beat in vanilla. Drop by teaspoon onto a nonstick baking sheet—or pipe the meringue from a pastry decorator. You should get two dozen kisses. Bake at 300 degrees for 25 minutes. Make a small indentation in each kiss and drop in a dab of lemon curd. To make lemon curd: Combine sugar and lemon juice in heavy medium saucepan. Stir in butter and eggs and beat well. Cook over medium heat for 8-10 minutes, stirring constantly, until mixture thickens. Pour into a one pint container and cover tightly. Refrigerate up to 2 months.