Step 1

Preheat the oven to 375°F (190°C).

Step 2

Heat 1 tablespoon of olive oil in a medium-sized skillet or sauté pan on medium heat. Add the onions and cook until translucent, stirring frequently for about 2 minutes. Add the chopped garlic and cook for 30 seconds more.

Step 3

Raise the heat to medium-high and add ½ tablespoon of olive oil to the pan. Add the mushrooms, ¼ teaspoon of salt, and pepper. Cook the mushrooms for 5-7 minutes, stirring occasionally.

Step 4

Pour in the chicken broth and bring to a simmer.

Step 5

Remove the pan from the heat and stir in the heavy cream, sour cream, ¼ teaspoon of salt, and dried rosemary.

Step 6

Pour the uncooked rice into a 4x6-inch or a 5x5-inch baking dish.

Step 7

Pour the mushroom cream sauce over the rice and stir gently. Place the baking dish on a rimmed baking sheet to catch any possible spills.

Step 8

Cover the casserole tightly with aluminum foil. Bake for 40 minutes and enjoy hot.