Melt butter in saucepan over very gentle heat. Mix in the sugar, oats and salt. Stir well and turn mixture into greased swiss roll tin and press lightly together. Smooth top surface with the back of a metal spoon and bake at 190 C for 30 - 35 mins in centre of oven. When golden brown remove from oven and allow to cool for a few minutes before cutting into finger slices. Cool completely before serving.