* Combine soda and syrup; set aside.
* Beat butter with an electric mixer until creamy. Gradually add sugar, beati ng well. Add eggs, one at a time, beating after each addition. Stir in syrup mixture.
* Combine flour and next 4 ingredients; add to butter mixture alternately with water, beginning and ending with flour mixture. Mix after each addition.
* Pour batter into a greased and floured 23 cm square pan. Bake at 180ºC for 30 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack at least 10 minutes before serving.