Heat oven to 400° F.
Wash and break the cauliflower into large florets. Bring a large pot of salted water to a rolling boil and drop in the florets. Boil the florets for about 5-8 minutes or until they are tender when pierced with a knife. Pour the florets carefully through a colander to drain.
Meanwhile, in a heavy saucepan over medium heat, melt the 6 butter. Whisk in the sweet white rice flour and cook over low heat, stirring, for about 2 minutes until a thick paste forms. Gradually pour the milk into the roux whisking constantly. Bring the sauce to a simmer and simmer, whisking, for about 5-10 minutes, until the sauce is very thick. Stir in all but a small handful of the grated cheese, the salt and pepper, and the dried herbs.
Arrange the florets in a baking dish, scatter the drained butter beans over the top, and pour over the cheese sauce over the entire dish. Scatter the surface with the rest of the cheese.
Place in the oven and bake for 30 minutes or so or until the sauce is bubbling at the edges. Remove, let stand for 5 minutes, and eat hot.
