Boil the sugar and water in a wide-bottomed pan without stirring. Reduce the heat and simmer, swirling the pan occasionally until a light brown caramel has formed. Remove the pan from the heat. Add the butter, stir into the caramel. Add the plums and cinnamon, simmer for approx. 5 mins. until soft.
To cook the pasta
Cook the pasta in salted water until al dente, drain.
Heat the butter in a pan. Toast the bread and nuts over a medium heat for approx. 3 mins., stirring occasionally. Sprinkle the crunchy topping on top of the pasta, serve with the plums.