Skinny Spinach Lasagna

Ingredients :
2 tablespoons butter
1 tablespoon minced garlic
2 teaspoons minced fresh thyme
6 ounces fresh spinach
2 lbs. ricotta cheese (I used 1 lb. whole milk and 1 lb. nonfat)
1 egg
½ teaspoon salt
¼ teaspoon nutmeg
a squeeze of lemon juice (optional, to taste)
12 no-boil lasagna noodles
1 24 ounce jar of spaghetti or marinara sauce (I used Trader Joe's tomato basil)
2 cups shredded mozzarella cheese

Instructions :
Melt the butter in a large skillet over medium heat. Add the garlic and thyme; saute for 2-3 minutes. Add the spinach; saute until just barely wilted, about 2 minutes. Remove from heat.
In a large bowl, combine the ricotta, egg, salt, nutmeg, and a squeeze of lemon juice. Add the spinach and stir to combine. Transfer some of the mixture to a food processor and pulse a few times to break up some of the spinach pieces (totally optional, but makes for a really nice texture).
Preheat the oven to 375 degrees. Spread a little bit of tomato sauce in the bottom of a 9x13 pan. Layer with 3 lasagna noodles, ⅓ of the spinach mixture, ¼ of the tomato sauce, and ¼ of the cheese. Repeat and pour ½ cup water over the two layers. Repeat once more, ending with noodles, sauce, and cheese. Pour ½ cup water over the whole thing again and cover tightly with oiled foil.
Bake for 30-40 minutes; when the liquid is bubbling and the noodles have softened, remove the foil and bake uncovered for 10 more minutes. Let stand for 10-15 minutes before serving so that the lasagna noodles can soak up all the extra moisture.