In a small bowl, combine the butter, thyme, lemon zest, garlic, and a generous pinch of salt and mash with a fork or spoon until well blended.
Put several large handfuls of the spinach in a 12-inch nonstick stir-fry or sauté pan. Season with 1/2 tsp. salt. Turn the heat to medium high and cook, stirring frequently, until the spinach is mostly wilted, 1 to 2 minutes. Add another few handfuls of spinach and another 1/2 tsp. salt, and continue to cook, tossing, until wilted. Repeat until all of the spinach is wilted. Turn off the heat, but leave the pan on the burner. Add the butter mixture and toss just until it melts and coats the spinach. Season to taste with salt and serve immediately.
Make Ahead Tips
You can make the butter mixture up to 2 days ahead (cover and refrigerate), and you can wilt the spinach up to 2 hours before dinner. Reheat it gently with the butter before serving.
nutrition information (per serving):
Photo: Scott Phillips