I love casseroles, pasta bakes, and gratins. What is not to love about dishes where you toss everything into a pan and let it cook until the cheese is melty and the top is browned? And now that the weather is cooling down, I can turn on the oven again without feeling like my house is a sauna. One of the perks of fall.

I find however that it is hard to get a beautiful picture of something so simple. Luckily, I worked with a wonderful photographer, Jessica Yager, who made this gratin look as good as it tasted.

This is a delicious side. It is rich and gooey, but still feels a little good for you because it is so green. The browned cheese on the top is my favorite part. I have made this for dinner parties and we also used it as a side at Thanksgiving last year. It makes a large quantity, so make it for a crowd, half it, or do like me and just eat it for lunch every day for the next week.

The last time I made this was served alongside Lemon Couscous and Lemon Roasted Chicken and it was delicious.

Spinach Gratin

Ingredients
4 tablespoons (1/2 stick) unsalted butter
4 cups chopped yellow onions (2 large)
1/4 cup flour
1/4 teaspoon grated nutmeg
1 cup heavy cream
2 cups milk
3 pounds frozen chopped spinach, defrosted (5 (10-ounce) packages)
1 cup freshly grated Parmesan cheese
1 tablespoon kosher salt
1/2 teaspoon freshly ground black pepper
1/2 cup grated Gruyere cheese

Directions
Preheat the oven to 425 degrees F.

Melt the butter in a heavy-bottomed saute pan over medium heat. Add the onions and saute until translucent, about 15 minutes. Add the flour and nutmeg and cook, stirring, for 2 more minutes. Add the cream and milk and cook until thickened.

Squeeze as much liquid as possible from the spinach and add the spinach to the sauce. Add 1/2 cup of the Parmesan cheese and mix well. Season, to taste, with salt and pepper.

Transfer the spinach to a baking dish and sprinkle the remaining 1/2 cup Parmesan and the Gruyere on top.Bake for 20 minutes until hot and bubbly. Serve hot.

Photographs by Jessica Yager