I make this recipe with some changes. More cheese, more ham, heavy cream instead of lowfat milk, and almond flour instead of bread crumbs. You don't need the flour at all when using heavy cream. It thickens on its own when you add the cheese. Also, instead of slices, I cut the ham and kohlrabi in cubes (about 0.5 inch cubes). It's really good.

http://www.eatingwell.com/recipes/kohlrabi_ham_gratin.html