Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Pat the chicken breast dry and cut into 1-inch bite-sized cubes, then halve the cremini mushrooms.
In a small bowl, whisk together the melted ghee, minced garlic, sea salt, black pepper, and dried thyme until well combined.
Place the chicken and mushrooms in a large mixing bowl and pour the garlic butter mixture over them, tossing until every piece is evenly coated.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the pieces are not overcrowded to allow for proper browning.
Roast for 18 to 20 minutes, or until the chicken is cooked through and the mushrooms are tender and golden.
Remove from the oven and immediately drizzle with fresh lemon juice to brighten the savory flavors.
Garnish with finely chopped fresh parsley and serve immediately while hot.