Pre-heat oven to 180°C (160°C fan-forced). Line the base and sides of 2 x 20cm cake pans.
Combine dates and water in a small saucepan. Bring to a boil. Remove from heat, stir in bi-carb and set aside.
Place butter and sugar in the bowl of an electric mixer and beat until pale and creamy. Add eggs one at a time, ensuring well combined before adding the next. Fold in the flour, cinnamon and date mixture, mixing until the batter is smooth. Pour batter evenly between prepared pans and bake for 35 minutes, or until cake springs back when gently pressed. Allow to cool for 10 minutes, before removing to a wire rack to cool completely.
Meanwhile for the sauce, combine sugar, cream and butter in a small saucepan. Bring to a boil, reduce heat to a simmer for 3-4 minutes. Remove from heat and set aside to cool.
Whip cream until soft peaks form, add mascarpone and continue mixing until mixture thickens.
For serving; cut each cake in half horizontally, place one layer on a serving plate, dollop on ¼ of the cream mixture and drizzle with some of the butterscotch sauce. Top with another layer of cake and continue until the final cake layer is on top. Dollop remaining cream on top and drizzle with more butterscotch sauce.