Trim cauliflower and cut into bite-size pieces. Finely chop garlic and parsley; grate Romano.
Bring a large pot of salted water to boil, then add pasta and cook 5 minutes less than the package instructions for al dente.
Add cauliflower and cook about 5 minutes more until pasta is al dente and cauliflower is tender. Drain pasta mixture, reserving 1 cup liquid; set aside.
In the same pot, heat oil over medium. Add garlic and cook about 1 minute until fragrant.
Add pasta mixture, Romano cheese, and 1/2 cup of the reserved cooking liquid; season with salt, pepper, and parsley to taste. Toss to coat, adding more liquid if necessary to thin the sauce.
Top with additional cheese if desired; serve apple slices and baby carrots on the side.