Gently mix in grated onion, minced garlic, panko breadcrumbs, egg, milk and seasonings (salt, pepper, allspice, nutmeg) until combined.
1 small onion, 2 garlic cloves, ½ cup panko breadcrumbs, 1 egg, ¼ cup whole milk, 1 teaspoon kosher salt, ½ teaspoon fresh ground black pepper, ¼ teaspoon allspice, ¼ teaspoon nutmeg