Photos by 
Jessicarobyn Keyser
Jessicarobyn Keyser

An Unforgotten Spinach-Mushroom Casserole

by 
Elise Seyfried
October 7, 2021

We all know about the ubiquitous guest at many a holiday table (not Uncle Joe, though him, too.) I'm talking about the cream of mushroom soup, green bean and fried onion ring casserole that someone always brings, overflowing its dish, semi-covered by a jaunty piece of aluminum foil. You can taste The Casserole now, can't you? Sorry about that, or, you’re welcome! 

For me, growing up with a militant non-cook (my mom Joanie), vegetables were a rare side dish. The Casserole was the only “complicated” vegetable dish served all year long (on Thanksgiving), and Mom dirtied every pot and pan in the kitchen in its preparation. The after-dinner cleanup involved scrubbing multiple dried globs of mushroom soup off the stovetop, and sweeping up enough fried onions to fill another can of them. One Thanksgiving, Mom just made The Casserole, left it on the dryer (who knows why?), and forgot to bring it to the table. No one noticed. Joanie actively resented fixing this dish, just as she resented every aspect of that food-centric holiday.The turkey was always rather pink, and if pumpkin pie was even on the menu, it was bought last-minute at the supermarket. There was never whipped cream. My sisters and I scampered off quickly to play, and my parents enjoyed their own preferred dessert, unfiltered Pall Mall cigarettes.

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When I grew up and had my own five kids (and learned to love vegetables and cooking), I was determined to re-invent The Casserole. I began to experiment with sauteed baby spinach, a rich wild mushroom sauce, and caramelized sweet onions.  Lo and behold, it works! The Casserole’s flavor combination was always basically a good idea, and by working with all fresh ingredients, those flavors have a chance to blossom. I use spinach because I prefer its rich taste to that of the green beans, but everything else is represented (namely mushrooms and onions). It takes a little while to prepare, but can be made ahead and reheated … which gives you time to cook that turkey properly, and maybe even whip up a homemade pie. But only if you enjoy cooking, and if spending time in the kitchen is fun for you. Thanksgiving should be whatever you want it to be.

Wild Mushroom, Spinach and Caramelized Onion Casserole

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 | 
Serve 6

Ingredients

1 large Vidalia or other sweet onion, peeled and thinly sliced

5 tbsp olive oil, divided

6 oz mixed sliced fresh wild mushrooms (shiitake, crimini, etc.)

1 large shallot, minced

½ cup dried porcini mushrooms

Sea salt

Coarse ground black pepper

1.5 cups heavy cream

1.5 cups grated Parmesan cheese

1 tsp fresh thyme or tarragon, minced (optional)

2 lbs baby spinach, fresh or frozen 

Panko crumbs

 | 
 | 
Serve 6

Ingredients

1 large Vidalia or other sweet onion, peeled and thinly sliced

5 tbsp olive oil, divided

6 oz mixed sliced fresh wild mushrooms (shiitake, crimini, etc.)

1 large shallot, minced

½ cup dried porcini mushrooms

Sea salt

Coarse ground black pepper

1.5 cups heavy cream

1.5 cups grated Parmesan cheese

1 tsp fresh thyme or tarragon, minced (optional)

2 lbs baby spinach, fresh or frozen 

Panko crumbs

Ingredients

1 large Vidalia or other sweet onion, peeled and thinly sliced

5 tbsp olive oil, divided

6 oz mixed sliced fresh wild mushrooms (shiitake, crimini, etc.)

1 large shallot, minced

½ cup dried porcini mushrooms

Sea salt

Coarse ground black pepper

1.5 cups heavy cream

1.5 cups grated Parmesan cheese

1 tsp fresh thyme or tarragon, minced (optional)

2 lbs baby spinach, fresh or frozen 

Panko crumbs

Directions

1. Preheat oven to 350 degrees

2. Heat large sauté pan with 1 tablespoon of the olive oil. Add onions and cook for five minutes to soften. Add a few grinds of sea salt. Turn heat down to medium low and continue cooking, stirring frequently, until onions are very soft, browned and caramelized (approx. 45 minutes). Set aside.

3. Place dried porcini mushrooms in a bowl and cover with boiling water. Let stand for 30 minutes. Drain, reserving strained liquid from mushrooms.  Chop softened mushrooms.

4. In a large skillet, sauté fresh wild mushrooms with minced shallot over medium high heat in 2 tablespoons of the olive oil until lightly browned. Add reserved strained liquid from dried mushrooms and the chopped porcinis, and cook over medium heat until most of the liquid is absorbed. Stir in reserved caramelized onions. Add the heavy cream and cook mixture over medium high heat until cream thickens (5-10 minutes). Stir in Parmesan cheese and optional herbs. Season with salt and pepper. 

5. In another large skillet, wilt fresh spinach or heat frozen spinach in remaining 2 tablespoons of olive oil over medium heat. Drain well and cool. Squeeze spinach to remove as much liquid as possible. 

6. In 9x9 dish, layer spinach with mushroom-onion cream sauce (spinach first, end with layer of sauce.) Sprinkle top generously with Panko.

7. Bake 15-20 minutes until heated through and bubbling.

About the Author

Elise Seyfried

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