Peel the kohlrabi and cut into eighths. Cook in the broth for 15 minutes. Drain and collect the broth. Make a sauce from butter, flour and broth. Mix the sour cream with the egg yolks and fold into the sauce. Season to taste with the spices. Place the kohlrabi pieces in a greased, flat baking dish. Spread the finely diced ham on top. Pour the sauce over them and bake at 225 ° C for about 15 minutes.