Step 1: Preheat the Oven. Set your oven to 375 °F (190 °C). If you’re using an oven-proof skillet or Dutch oven for both stovetop and oven, there’s no need to transfer later. Otherwise, plan to pour into a greased 9×9-inch baking dish at bake time.
Step 2: Brown the Beef. In your skillet over medium-high heat, warm the olive oil until shimmering. Add the ground beef, season generously with salt and pepper, and cook—breaking it up with a spoon—until there’s no pink visible, about 5 minutes. Transfer the browned beef to a bowl and set aside, leaving any rendered juices in the pan.
Step 3: Sauté Aromatics & Mushrooms. Reduce heat to medium. Add the diced onion and cook for 2–3 minutes, stirring, until translucent. Stir in the minced garlic and dried thyme, cooking for 30 seconds until fragrant. Add the sliced mushrooms; season lightly with salt and pepper. Sauté for 4–5 minutes, until the mushrooms have released their moisture and are nicely browned.
Step 4: Toast the Rice. Stir the rinsed long-grain rice into the mushroom–onion mixture, ensuring each grain is coated in oil and pan juices. Cook for about 1 minute, stirring constantly, until you notice a faint nutty aroma—this step keeps the rice from becoming mushy and helps it absorb the liquid evenly.
Step 5: Build the Creamy Base. Return the reserved browned beef to the skillet. Pour in the low-sodium chicken broth and heavy cream, stirring gently to combine with the rice and vegetables. Increase heat to medium-high and bring the mixture to a gentle simmer, scraping up any browned bits from the bottom of the pan. Allow it to bubble for 2–3 minutes, until the liquid volume reduces slightly and the sauce begins to coat the rice.
Step 6: Top with Cheese. Evenly distribute the shredded sharp cheddar and grated Parmesan over the surface of the creamy rice and beef mixture. Do not stir—this layer of cheese will melt into a golden, bubbly crust as it bakes, sealing in moisture and adding a rich, savory finish.
Step 7: Bake Until Bubbly. Transfer the skillet (or pour contents into a greased 9×9-inch baking dish) to the preheated 375 °F (190 °C) oven. Bake for 20–25 minutes, or until the cheese topping is fully melted, bubbling, and has developed light golden-brown spots.
Step 8: Rest & Garnish. Remove the bake from the oven and let it rest for 5 minutes. This brief resting period allows the sauce to thicken slightly, ensuring each scoop holds its shape. Sprinkle the chopped fresh parsley over the top for a bright, herbaceous contrast.
Step 9: Serve. Using a wide spatula or serving spoon, scoop generous portions onto warmed plates or into shallow bowls. Aim to include both creamy rice underneath and a bit of the crisp cheese crust on top in every serving.
Step 10: Enjoy. Serve immediately alongside a simple green salad or steamed vegetables for a balanced meal. The combination of tender beef, earthy mushrooms, creamy rice, and that irresistible cheesy crust makes this dish a guaranteed crowd-pleaser.