Rinse the brown rice well, and cover with cold water (twice the amount of rice). Bring to boil and cook till all the water has gone. Takes about 20 minutes. (I do this in the morning, so when I come back to make dinner, I am dealing with cold cooked brown rice.)
Chop the cauli' up, roughly, into small pieces, so they cook quite quickly. Small florets are fine. Cover with hot stock / milk and bring to boil, then reduce to a simmer. The liquid needs to cover the cauliflower so it cooks evenly. Once it's cooked, after about 10-15 minutes, blitz in a food processor. You want a thick soup consistency. If it's a little too thin, don't worry, just don't put as much in - leftovers are nice as soup! If it's too thick, simply add a little more milk.
Meanwhile, sweat the onion and garlic for about 5 minutes, to soften. Add the herbs, and prosciutto and cook a little more, so the meat crisps up a little. Tip in the cooked rice (warm or cold), and heat through. Add the cauliflower sauce, stir to combine. Scatter the chopped cheese through and let it melt, stirring gently. Let it heat through to a gently bubble. Season to taste, then serve. Be very smug that your kids are eating brown rice and loving it!