Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Clean the cremini mushrooms with a damp cloth to remove any debris and halve any large ones so they are uniform in size.
Slice the chicken breast into bite-sized 1-inch pieces to ensure they cook evenly with the mushrooms.
In a small bowl, whisk together the melted ghee, extra virgin olive oil, minced garlic, and fresh thyme leaves.
Place the chicken and mushrooms on the prepared baking sheet, then drizzle with the garlic-ghee mixture.
Sprinkle with sea salt and black pepper, then toss everything thoroughly to ensure every piece is well-coated.
Spread the mixture in a single layer, ensuring no crowding to allow for proper browning and caramelization.
Roast for 18-20 minutes, or until the chicken is cooked through and the mushrooms are tender and golden brown.
Remove from the oven and garnish with fresh chopped parsley before serving warm.