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Mushroom Walnut Au Gratin: A Vegetarian Classic Reimagined

The scent of toasted walnuts and earthy mushrooms baking in the oven takes me back to my college days. The Good Earth restaurant, a haven for health-conscious students, was where I first encountered this comforting dish. It was a welcome departure from dorm food and a delicious way to fill up on something other than ramen. I remember the warmth of the restaurant, the lively conversations, and the satisfying feeling of a hearty, vegetarian meal that truly hit the spot. Even decades later, the memory of that first bite still lingers.

Recipe Overview

Prep Time: 30 minutes
Cook Time: 50 minutes
Total Time: 1 hour 20 minutes
Servings: 4-6
Yield: One 2 1/2 quart baking dish
Dietary Type: Vegetarian

Ingredients

For the Brown Rice Pilaf:

2 tablespoons vegetable oil
¾ cup uncooked brown rice
1 small onion, finely chopped
1 vegetable bouillon cube
½ teaspoon salt
¼ teaspoon ground ginger
¼ teaspoon oregano, crumbled
1 ½ cups water

For the Mushroom Walnut Mixture:

3 tablespoons vegetable oil
1 cup walnuts, coarsely chopped
2 medium onions, cut into quarters and thinly sliced
½ lb mushrooms, sliced
3 cups thinly sliced broccoli (stems and bite-sized florets)
½ cup slivered water chestnuts
1 clove garlic, minced
1 tablespoon soy sauce
½ cup sour cream
1 cup shredded Monterey Jack cheese
1 cup shredded Cheddar cheese
Orange slice (to garnish, optional)

Equipment Needed

2-quart saucepan
Large skillet
Slotted spoon
Greased, shallow 2 1/2 quart baking dish

Instructions

Begin by preparing the brown rice pilaf. In a 2-quart saucepan, heat 2 tablespoons of vegetable oil over medium heat.
Add ¾ cup of uncooked brown rice to the heated oil. Stir continuously until the rice begins to brown slightly. This toasting process adds a nutty depth of flavor to the pilaf.
Incorporate 1 small onion, finely chopped, into the rice. Stir until the onion is lightly browned and fragrant.
Introduce the flavor enhancers: 1 vegetable bouillon cube, ½ teaspoon salt, ¼ teaspoon ground ginger, and ¼ teaspoon oregano, crumbled. Stir well to combine all ingredients evenly.
Pour in 1 ½ cups of water, stirring to ensure the bouillon cube is fully dissolved.
Cover the saucepan and lower the heat to a gentle simmer. Allow the rice to cook undisturbed until it is just tender, approximately 30 minutes. Resist the urge to lift the lid and peek, as this will release steam and prolong the cooking time.
While the rice is simmering, preheat your oven to 400 degrees Fahrenheit (200 degrees Celsius).
Prepare the mushroom walnut mixture. In a large skillet, heat 3 tablespoons of vegetable oil over medium-high heat.
Add 1 cup of walnuts, coarsely chopped, to the heated oil. Stir frequently until the walnuts are lightly browned and fragrant, ensuring they don’t burn.
Using a slotted spoon, carefully remove the toasted walnuts from the skillet and reserve them in a separate bowl.
Introduce 2 medium onions, cut into quarters and thinly sliced, and ½ lb of mushrooms, sliced, to the remaining oil in the skillet. Brown lightly, then remove them with a slotted spoon and reserve with the walnuts.
Add 3 cups of thinly sliced broccoli (both stems and bite-sized florets) to the skillet. Sauté until the broccoli is crisp-tender, about 8 minutes. The stems will take a bit longer to cook than the florets, so ensure they are sufficiently tender before moving on.
Stir in the reserved onions, mushrooms, and ½ cup of slivered water chestnuts, along with 1 clove garlic, minced. Cook for another minute until the garlic is fragrant.
Remove the skillet from the heat. Add the reserved walnuts, 1 tablespoon soy sauce, and ½ cup sour cream.
Stir lightly to coat all the vegetables evenly with the sour cream mixture.
Spread the cooked brown rice pilaf evenly in a greased, shallow 2 ½ quart baking dish.
Cover the pilaf with the prepared vegetable mixture, distributing it uniformly over the rice.
Sprinkle 1 cup of shredded Monterey Jack cheese and 1 cup of shredded Cheddar cheese evenly over the vegetable mixture.
Bake in the preheated oven until the cheese is melted and bubbly, about 20 minutes.
Allow the au gratin to cool slightly before serving. Garnish with an orange slice, if desired.

Expert Tips & Tricks

Toast the walnuts carefully: Over-toasted walnuts can become bitter. Watch them closely and stir frequently.
Don’t overcrowd the skillet: If you overcrowd the skillet with onions and mushrooms, they will steam instead of brown. Cook them in batches if necessary.
Broccoli prep: To ensure even cooking, slice the broccoli stems thinly.
Cheese blend: Feel free to experiment with different cheese combinations. Gruyere or Swiss cheese would also work well.
Make ahead: The pilaf and the mushroom walnut mixture can be prepared a day in advance and stored separately in the refrigerator. Assemble and bake just before serving.
Spice it up: Add a pinch of red pepper flakes to the vegetable mixture for a little heat.

Serving & Storage Suggestions

Serve the Mushroom Walnut Au Gratin hot, straight from the oven. It makes a satisfying main course or a substantial side dish. Leftovers should be stored in an airtight container in the refrigerator. It will last for about 3-4 days. Reheat in the oven or microwave until warmed through. While freezing is possible, the texture of the sour cream and cheese may change slightly upon thawing.

Nutritional Information

Nutrient	Amount per Serving	% Daily Value
Calories	650 kcal	33%
Total Fat	45g	58%
Saturated Fat	15g	75%
Cholesterol	50mg	17%
Sodium	700mg	30%
Carbohydrates	40g	15%
Fiber	6g	24%
Sugar	6g	N/A
Protein	20g	40%

Note: Nutritional information is an estimate and may vary based on specific ingredients and portion sizes.

Variations & Substitutions

Gluten-free: Ensure the soy sauce is gluten-free (tamari is a good option).
Vegan: Substitute the sour cream with a plant-based alternative like cashew cream or tofu sour cream. Use vegan cheese.
Different vegetables: Feel free to add other vegetables like bell peppers, zucchini, or spinach.
Nut variations: Pecans or hazelnuts can be used in place of walnuts.
Herbs: Fresh thyme or rosemary would be a lovely addition to the vegetable mixture.

FAQs (Frequently Asked Questions)

Q: Can I use pre-cooked rice for the pilaf?
A: While you can use pre-cooked rice, the texture won’t be quite the same. Cooking the rice from scratch allows it to absorb more flavor and creates a slightly stickier texture that works well in this dish.

Q: Can I make this dish ahead of time?
A: Yes, you can prepare all the components ahead of time and assemble it just before baking. This makes it a great option for entertaining.

Q: What is the best way to reheat leftovers?
A: Reheat in the oven at 350°F (175°C) until warmed through, or microwave in short bursts, stirring occasionally, to prevent hot spots.

Q: Can I use different types of mushrooms?
A: Absolutely! Feel free to experiment with different mushroom varieties like cremini, shiitake, or oyster mushrooms for a more complex flavor profile.

Q: What can I serve with this dish?
A: This Mushroom Walnut Au Gratin pairs well with a simple green salad, roasted vegetables, or a crusty loaf of bread.

Final Thoughts

This Mushroom Walnut Au Gratin is more than just a recipe; it’s a journey back in time, a celebration of simple ingredients, and a testament to the enduring appeal of vegetarian comfort food. I encourage you to try this recipe and create your own memories with it. Feel free to experiment with variations and make it your own. I’d love to hear about your experiences and any creative twists you add! Pair it with a crisp white wine or a hearty red for a truly satisfying meal. Happy cooking!

Mushroom Walnut Au Gratin Recipe