Preheat oven to 325. Lightly grease a 9x13 pan. In a small sauspan, combine sugar, butter and water; bring just to a boil. Remove from the heat add semi sweet morsels and 2 teasp. vanilla, stir until chocolate melts. Transfer chocolate mixture to large bowl. Beat in 4 eggs, one at a time. Combine flour, soda and salt, gradually add to chocolate mixture, mix thoroughly, add nuts. Spread into a greased pan. Bake at 325 for 45 to 50 minutes. Check at 40 minutes, due to ovens varying temperature. Do not overbake, take out as soon as tester comes out clean.