1.Preheat oven to 180°C (160°C fan-forced). Grease deep 22cm round cake pan and line base with baking paper.
2.Bring figs and the water to the boil in small saucepan. Remove from heat, add soda; cover, stand 5 minutes. Blend or process until smooth.
3.Beat butter and sugar in small bowl with electric mixer until light and fluffy. Beat in eggs one at a time. Transfer mixture to large bowl and stir in sifted flour, ground almonds and chopped nuts, then fig mixture. Pour mixture into pan.
4.Bake cake about 1 hour. Stand cake in pan 10 minutes before turning onto wire rack to cool.
5.Meanwhile, to make butterscotch sauce, stir ingredients together in a small saucepan over heat, without boiling, until sugar dissolves. Simmer, without stirring, 3 minutes.
6.Slice cake and drizzle with butterscotch sauce. Serve with whipped cream.