The cooler season begs for layers — and not just when it comes to clothing. Behold the lasagna. This hefty casserole is layered with three cheeses, a meaty tomato sauce and — wait for it — kale.

Now, before you roll your eyes, realize this: This lasagna can handle a little kale. In fact, it will put the hearty greens in their place, allowing them to shine without overtaking this admittedly nonvegetarian recipe with excessive leafiness. It will invite a layer of freshness into an otherwise robust, gooey and loaded lasagna. And if you are trying to sneak a few vegetables into someone’s diet, this may do the trick.

With that preface, let me add that this recipe can easily be made vegetarian by simply omitting the meat from the tomato sauce. The choice is yours, and both versions are delicious. I’ve provided a meat sauce in the recipe, but you can skip it if you prefer. And if you have a favorite prepared sauce that you swear by, then by all means, make your life a little easier and use it.

Now, back to the layers. Stack your lasagna as high as your dish will allow (let’s hope it’s at least 2 1/2 inches deep). And do include kale leaves in the mix. They will soften and melt into the lasagna, tempered by the rich cheese and bright sauce, while providing color and, of course, extra nutrients. You might even have room for seconds.

Lasagna

Active Time: 45 minutes

Total Time: 1 hour and 45 minutes

Yield: Makes one 9-inch-square lasagna. For a larger rectangular lasagna (pictured), double the ingredients.

Sauce:

1 tablespoon olive oil

1/2 pound ground beef

1 small yellow onion, finely chopped

2 garlic cloves, minced

1/4 teaspoon crushed red pepper

1 (28-ounce) can crushed Italian plum tomatoes

2 tablespoons tomato paste

1 teaspoon dried oregano

1/2 teaspoon sugar

Salt and freshly ground black pepper to taste

Ricotta:

16 ounces whole-milk ricotta

1 large egg, lightly beaten

1/4 cup finely grated Parmesan cheese

2 tablespoons half-and-half

1 garlic clove, minced

1/2 teaspoon salt

1/4 teaspoon freshly ground black pepper

1 box lasagna sheets

One bunch Tuscan (Lacinato) kale leaves, ribs removed, torn into large pieces

8 ounces fresh mozzarella, shredded

1 cup finely grated Parmesan and/or Pecorino Romano cheese

Make the sauce: Heat the oil in a medium saucepan over medium heat. Add the beef (if using) and cook until lightly browned, 5 to 7 minutes, stirring as needed. Add the onion and cook until softened, about 3 minutes, stirring often. Add the garlic and crushed red pepper and cook until fragrant, about 1 minute.

Stir in the remaining sauce ingredients and simmer uncovered for 25 minutes, stirring occasionally.

Whisk the ricotta ingredients in a bowl until smooth.

Heat the oven to 375 degrees.

Spoon a thin layer of sauce in bottom of a baking dish. Place a layer of lasagna sheets over the sauce, breaking them to fit to size as necessary. Smear some of the ricotta over the lasagna sheets. Arrange some of the kale leaves over the ricotta and drizzle some of the sauce over the kale. Scatter some mozzarella over the kale and sprinkle with grated cheese. Repeat the layering process, gently pressing down on the layers as you stack the lasagna. (You may not use up all of lasagna sheets.)

Cover the dish with foil, transfer to the oven, and bake for 40 minutes. Remove the foil and continue to bake until the lasagna sheets are tender when pierced with a knife, the cheese is bubbling and the top is golden brown, 15 to 20 minutes. Let stand 10 minutes before cutting and serving.