Blend the flour, butter, and sugars. Take out a ½ cup of the mixture.
To the rest, add the buttermilk, soda, egg, and vanilla. Blend well. Pour into a greased and floured 10x14x2 inch cake pan. (I used a 13x9 cake pan)
Crush finely the toffee bars with the nuts and add to the ½ cup of reserved mixture. Sprinkle over the top of the batter and bake in a 350-degree oven for 30 minutes.