Preheat your oven to 400°F (200°C).
Season the chicken breast evenly with sea salt and black pepper.
In a large oven-safe skillet over medium-high heat, melt the ghee until shimmering.
Add the chicken breast to the skillet and sear for 3-4 minutes per side until golden brown, then remove and set aside.
In the same skillet, add the sliced cremini mushrooms and sauté for 5 minutes until they begin to release their moisture and soften.
Stir in the minced garlic and fresh thyme, cooking for 1 minute until highly aromatic.
Place the chicken back into the skillet, nestling it among the mushrooms, and transfer the pan to the oven.
Roast for 10-12 minutes or until the chicken reaches an internal temperature of 165°F.
Remove from the oven and sprinkle with fresh parsley and grated parmesan cheese.
Serve the roasted chicken and mushrooms over a bed of fresh baby spinach, allowing the warm juices to slightly wilt the greens.