How to Make It
Remove any tough stems from the spinach. In a large frying pan, melt the butter over moderately low heat. Add the scallions and tarragon and cook for 2 minutes. Add the spinach and salt and stir until wilted. Simmer until the liquid evaporates from the spinach, about 5 minutes.
In a large pot of boiling, salted water, cook the spaghetti until just done, about 12 minutes. Reserve 1 cup of the pasta water. Drain the spaghetti and toss with 3/4 cup of the reserved pasta water, the spinach mixture, the cream cheese, parsley, Parmesan, and pepper. If the sauce seems too thick, add more of the reserved pasta water.
Spinach Options You can buy fresh spinach in various forms, depending on how hard you want to work.
• Salad bar Weigh out 10 ounces of spinach from your supermarket's salad bar, and you're ready to cook—no rinsing or stem removal required.
• Prewashed bags Supermarkets carry 10-ounce bags of spinach. This has been cleaned of all visible sand, but we would still give it one final rinse before cooking.
• Bunches of fresh spinach You will need 1 1/2 pounds to equal 10 ounces of packaged cleaned spinach. Remove the stems and then wash the leaves several times to get rid of the grit.