Heat a frying pan and add chopped walnuts. Shake the pan to turn the nuts. When you start to smell them toasting, turn off the heat. Transfer toasted nuts to a bowl.
Remove stems from spinach. Rinse and drain in a colander and pat with a paper towel. Heat oil in the frying pan and sauté spinach until soft and bright green. Add raisins and nuts and stir until hot. Serve immediately.