Adjust rack in lower third of oven and preheat to
350 degrees F. Grease and flour a 9 x 13 x 2-inch baking pan. Sift the flour,
granulated sugar, salt and 1/2 teaspoon cinnamon into a large bowl. Using a
rubber spatula or whisk briefly mix in the brown sugar to blend ingredients
together. Stir in the oil, mixing well.
For the topping, remove 3/4 cup, loosely
packed, from the mixture. Add the nuts and the remaining cinnamon and with
fingertips, blend well; set aside.
To the remaining mixture, stir in the baking
powder and baking soda. Blend in thoroughly the egg and buttermilk until
mixture is smooth. Pour into prepared baking pan. Sprinkle topping mixture
evenly over batter. Bake for about 35 minutes or until a toothpick inserted in
the center comes out free of cake.
