Place all of the raisins in a small bowl and cover with water. Put to one side and leave them to rehydrate.
To prepare the spinach, wash any dirt or soil off of the leaves, and trim the stalks (not necessary if using baby spinach). Once clean, place in a large pot with the salt and water over medium heat. Cook, stirring, for 3-4 minutes or until the spinach is wilted.
Strain through a colander and gently squeeze with your hands to remove any excess water. Leave in a colander over a bowl to continue draining.
Place a large skillet or frying pan over medium-low heat and add the pine nuts. Toast the pine nuts until they are lightly golden brown, about 1-2 minutes. Shake the pan quite a bit to move the nuts around and toast evenly on all sides. Remove the nuts from the pan and place on a plate to one side.
Put the pan back on the heat. Add the olive oil and increase the heat to medium. When the olive oil is hot, add the garlic and begin to fry until lightly golden (about 1-2 minutes).
Drain the raisins and add them to the pan. Also add the spinach, stirring to mix together with the raisins and garlic. Cook, stirring constantly, until any excess water has evaporated completely.
Add the pine nuts back into the pan and stir to combine everything.
Remove the pan from heat and serve immediately. Season with salt, pepper, and more olive oil.