In a medium sized pot, melt the butter over medium heat.
Add the garlic & rosemary and saute for about 1 minute.
Add the prosciutto and continue to cook, stirring occasionally for about 2 more minutes.
Mix in the flour and cook for another minute or two, stirring the whole time.
Add in the milk 1/2 c at a time and mix in thoroughly each time. The milk should thicken as it is mixed in. Once all the milk has been added, you want the mixture to be thick enough to coat the back of a spoon.
Add the cauliflower, and coat thoroughly with the milk mixture. Heat to a boil, then remove from the heat.
Spread the mixture evenly in a small baking dish (mine is 9x 6).
Spread the swiss & and mozzarella cheese evenly on top.
Bake for 20-25 minutes until the cheese is bubbly and brown on top.