Quinoa Cakes With Mushroom Kale Alfredo Sauce

2 tablespoon olive oil ½ cup chopped onion 4 cloves garlic, minced 1 2 pound head cauliflower, trimmed and cut into florets 2 cup reduced-sodium chicken broth ¾ cup finely shredded Parmigiano-Reggiano cheese ½ cup milk ¼ teaspoon salt ¼ teaspoon black pepper