Soften gelatin using package directions. Combine 1/2 of the apple with gelatin in bowl. Let stand 10 minutes. Combine remaining 1/2 cup apple, sugar and lemon juice in large saucepan; mix well. Stir in gelatin-apple mixture. Bring to a boil. Simmer 15 minutes. Cool for 30 minutes. Add hazelnuts and vanilla; mix well. Pour into greased 8x8 " pan. Let stand for 24 hours. Cut into squares. Roll in mixture of confectioners sugar & cornstarch.