Soak gluten-free rolled oats in milk to rehydrate them.
Sauté onions and carrots.
Combine soaked oats with sautéed onions, carrots, cashews, egg, and parsley.
Form the mixture into cakes using a ¼-cup measure in the pan.
Flatten the cakes with a spatula.
Serve hot with horseradish dipping sauce.
Pair with sautéed greens.