Saute the onion in 2 tablespoons butter in a covered pan. Peel the kohlrabi to remove the woody outer layer. Slice thinly and layer with the onions and seasoning in a 3 pint lightly buttered shallow ovenproof dish. Top with a neat layer of kohlrabi. Pour over the milk and dot with remaining butter. Place on a baking tray and cook in the oven at 400°F for about 1-1/2 hours, until tender. Garnish with chopped parsley for serving.

Serves 6