Making boiled spinach is usually the best technique to use when you need to puree your spinach, or when you need it to look and feel the way (thawed) frozen Spinach looks and feels.
Place clean, de-stemmed Spinach in boiling water (no need to chop first) for 2-3 minutes. Drain in a colander.
(To stop the cooking immediately, you can plunge the cooked spinach into a bowl of ice water.)
Cooked spinach tends to hold a LOT of moisture. You may or may not want that moisture in your recipe. If not, squeeze it dry either with clean hands, or by pinching the spinach against the side of the colander with the back of a large spoon or fork.