To a large bowl, add about 1/2 cup of béchamel sauce. Also, add a splash of pasta water or gluten free chicken broth if the sauce has become too thick. Add the pasta and about another 1/2 cup of sauce; toss to combine. Add the vegetables and a little more sauce to your liking and toss. Toss in fresh basil if desired.
https://glutenfreerecipebox.com/gluten-free-cauliflower-and-broccoli-cheese-pasta-bake/