Put the rice in a medium saucepan and cover with water by 2 inches. Bring to a boil, reduce the heat, and simmer until the rice is tender, about 30 minutes. It should still have a little bite to it.

Heat the oven to 300 degrees F. Have ready a shallow, 2-quart baking dish. When the rice is cooked, drain it well in a fine-mesh sieve and put it in the baking dish. Add the brown sugar, raisins, vanilla, cinnamon, nutmeg, and salt to the rice. Wipe out the rice saucepan and add the evaporated milk and heavy cream. Over medium-high heat, bring the liquids barely to a boil and then pour them into the baking dish. Stir the mixture a few times until the ingredients are well dispersed and the sugar has dissolved. Bake until the top is browned, the liquid is reduced and thick, and the rice is tender, 1-1/2 to 2 hours.

In a small skillet over medium heat, melt the butter. Add the chopped nuts and sprinkle on the sugar. Cook over medium heat, stirring often to ensure even browning, until the nuts are toasted and the sugar is caramelized, about 10 minutes. Remove from the heat and immediately transfer to a bowl to cool completely. Just before serving, break the cooled nut topping apart and scatter over the entire pudding before serving.