Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Clean the cremini mushrooms with a damp cloth and slice them into halves or quarters if they are large.
Trim the woody ends off the asparagus and cut the chicken breast into even 1-inch bite-sized pieces.
In a small bowl, whisk together the melted ghee, minced garlic, chopped fresh thyme, sea salt, and black pepper.
Place the chicken, mushrooms, and asparagus on the sheet pan in a single layer.
Drizzle the garlic ghee mixture over the ingredients and toss thoroughly to ensure everything is well-coated.
Roast in the center of the oven for 18-22 minutes, or until the chicken is cooked through and the mushrooms are caramelized.
Remove from the oven and finish with a bright squeeze of fresh lemon juice before serving.