Cream butter, gradually add 1 cup sugar & 1/2 cup brown sugar, beating well. Add eggs one at a time, beating well after each addition. Stir in vanilla. Combine flour and 1 teaspoon cinnamon. Add to creamed mixture alternately with buttermilk, beginning and ending with flour mixture. Mix well after each addition. Pour batter into a greased and floured 13X9X2 pan. Combine pecans, 1/2 cup brown sugar and 1/'2 teaspoon cinnamon. Stir well and sprinkle over batter.

Cover and chill 8-10 hours or overnight. Uncover batter and let come to room temperature. Bake at 350 for 35 minutes or until wooden toothpick inserted in center comes out clean. 12-15 servings.