Preparing mushroom casserole is simple when you follow these easy steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Sauté Vegetables: In a large skillet, heat olive oil over medium heat. Add chopped onions and minced garlic, cooking until soft and fragrant.
3. Add Mushrooms: Introduce sliced mushrooms to the skillet and sauté until they release their moisture and become tender, about 5-7 minutes.
4. Prepare Rice: In a large mixing bowl, combine the sautéed mushrooms, cooked rice, vegetable or chicken broth, heavy cream, thyme, salt, and pepper. Stir until well combined.
5. Add Cheese: Fold in half of the shredded cheddar cheese into the mushroom and rice mixture.
6. Transfer to Baking Dish: Pour the mixture into a greased 9×13 inch baking dish, spreading it evenly.
7. Top with Breadcrumbs: Sprinkle the remaining cheddar cheese over the top, then add breadcrumbs for a crunchy golden topping.
8. Bake: Place the baking dish in the preheated oven and bake for 30-35 minutes or until the top is golden brown and bubbly.
9. Cool Slightly: Remove from the oven and allow it to cool for a few minutes before serving.
10. Garnish and Serve: Garnish with chopped parsley for a fresh touch.

By following these steps, you’re on your way to creating a delicious mushroom casserole that will impress and comfort everyone at your table.