Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Cut the chicken breast into 1-inch bite-sized pieces and halve the cremini mushrooms, leaving smaller ones whole.
In a small bowl, combine the ghee, olive oil, minced garlic, chopped thyme, sea salt, and black pepper.
Place the chicken and mushrooms on the prepared baking sheet and drizzle with the garlic-herb mixture, tossing thoroughly to coat.
Spread the ingredients into a single layer, ensuring they aren't overcrowded to allow for proper roasting.
Roast for 18-20 minutes, or until the chicken is cooked through and the mushrooms are tender and caramelized.
Remove from the oven, drizzle with fresh lemon juice, and garnish with freshly chopped parsley before serving.