Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Slice the chicken breast into 1-inch bite-sized pieces and halve the cremini mushrooms.
Trim the woody ends off the asparagus spears and cut them into 2-inch segments.
In a small bowl, melt the ghee and whisk in the minced garlic, sea salt, and black pepper.
Place the chicken, mushrooms, and asparagus on the prepared baking sheet and drizzle with the garlic-ghee mixture.
Toss everything thoroughly to ensure an even coating of the fat and seasonings, then spread into a single layer.
Roast for 18 to 20 minutes until the chicken is cooked through and the mushrooms have developed a golden, caramelized exterior.
Remove from the oven, drizzle with fresh lemon juice, and garnish with fresh thyme leaves before serving hot.