Make the stock: Sauté shallots in olive oil until translucent. Add mushrooms and cook until tender. Deglaze with sherry, then add broth. Once hot, blend until smooth with parsley, salt, and pepper.
Cook the amaranth: In a large pot, heat coconut oil and sauté shallots. Add amaranth and toast briefly. Gradually stir in hot mushroom stock, ½ cup at a time, until absorbed and grains are tender (about 20 minutes). Season to taste.
Finish and serve: Spoon amaranth into bowls, top with cauliflower, drizzle with olive oil, and add Pecorino if desired.