1In large mixing bowl, mix first 5 ingredients on low until resembles coarse meal.
RESERVE one cup for topping.
2To remaining ingredients, add buttermilk,soda,egg,& vanilla. Mix just until combined.Pour into buttered 9 x 13 pan In small bowl, mix pecans & heath bar. Pour wet into dry reserving Toffee mixture.
Mix leftover 1/2 cup dry mix with toffee /nut mixture.
3Sprinkle over batter in pan. Bake at 350 for 30-35 minutes. Tooth pick test. Cool completely because if you cut too soon it will be mushy!