Cook until liquid is almost gone, stirring to prevent sticking and burning (3 to 4 hours). Add oil and cook more, stirring often, to roast the carrots well (about 1/2 hour). Add the powdered milk and sugar and cook until all the liquid is gone and the mass does not stick to the sides. Add the nuts and raisins and turn off the heat. Pour in a serving dish and serve warm or cold. Will keep in the refrigerator for up to 1 week.