Melt your butter in a large skillet to which you have a top. Wash your turnips and cut them into 1/4 inch slices (no need to peel anything!).
Layer the slices in the pan and sprinkle the sliced turnips with your assembled spices. Cook for 3 minutes over medium heat, then pour your heavy cream and stock over the top. Cover and cook the turnips over medium heat for 20 minutes. The turnips will be completely cooked through, but there will be considerable liquid left in the pan.
Remove the cover and cook to reduce the liquid. When most of the liquid has reduced (5-10 minutes) and the sauce is thickened, pour your cheese evenly over the top. Watch closely as the cheese melts and make sure that the liquid does not completely cook off.