Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Pat the chicken breast dry with paper towels and cut into uniform 1-inch bite-sized pieces.
Clean the cremini mushrooms with a damp cloth and slice them into halves or quarters if they are large.
In a small bowl, whisk together the melted ghee, minced garlic, chopped thyme, and chopped rosemary.
Place the chicken and mushrooms on the prepared baking sheet, then drizzle with the garlic-herb ghee and sprinkle with sea salt and black pepper.
Toss everything together until well-coated and spread into a single layer to ensure even roasting.
Roast for 18 to 20 minutes, tossing halfway through, until the chicken is cooked through and the mushrooms are beautifully browned.
Remove from the oven, drizzle with fresh lemon juice, and garnish with chopped parsley before serving.