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 cubes.
Clean the cremini mushrooms with a damp cloth and halve any that are particularly large.
Rinse the cannellini beans thoroughly in a fine-mesh sieve and pat dry with a towel to ensure they crisp up in the oven.
Mince the garlic cloves finely and strip the leaves from the fresh thyme sprigs.
In a small bowl, whisk together the melted ghee, minced garlic, sea salt, black pepper, and fresh thyme.
In a large mixing bowl, combine the chicken cubes, mushrooms, and beans, then pour the garlic-ghee mixture over them and toss to coat evenly.
Spread the mixture in a single layer on the prepared baking sheet, ensuring pieces are not overcrowded to allow for proper browning.
Roast for 18 to 20 minutes, or until the chicken reaches an internal temperature of 165°F and the mushrooms are golden brown.
Remove from the oven and drizzle with fresh lemon juice before serving warm.