This came from On Top of Spaghetti, a fine cookbook.

Spaghetti with Fresh Spinach and Gorgonzola

• 4 Oz. Gorgonzola, at room temperature
• 4 Tbsp. unsalted butter, at room temperature
• 8 C. firmly packed trimmed young, fresh spinach
• 2 Tbsp. extra virgin olive oil
• 2 tsp. sea salt
• 1 lb. dried spaghetti or spaghettini
• 10-12 large fresh basil leaves (optional)

1. Bring a large pot of water to a boil for the pasta.
2. In a small bowl, mush together the Gorgonzola and butter until you have a smooth paste.  Set aside but do not refrigerate.
3. Wash the spinach in plenty of cold water.  Drain in a a colander, leaving the water clinging to the leaves.
4. Heat the olive oil in a large straight-sided skillet over moderately high heat.  Add the spinach and 1 tsp. of the salt. Toss the spinach with tongs until it has wilted.  Taste it and add more salt if necessary.  Turn off the heat but keep the spanach warm on the side of the stove.
5. Generously salt the pasta water and drop in the spagheti. Cook at a rolling boil, stirring often until al dente.  Drain the pasta, reserving about 1 cup of the cooking water. Transfer the spaghetti to the skillet and toss with the spinach.  Add the Gorgonzola-butter mixture and toss to coat each strand of spaghetti.  If the pasta seems dry, add a bit of cooking water and toss again.  Add as much of the cooking water as you need to make a creamy consistency.  If you have fresh basil, tear the leaves and toss into the spaghetti.