Place a casserole pan on a medium heat and melt half the butter with a splash of oil. Season and brown the veal on all sides, then remove from pan and set aside.
Peel and finely slice the onions and garlic, then trim and cut the leeks into large chunks. Sauté in the same pan until soft but not coloured, then add the carrots and cook for a few minutes.
Make a space in the middle, and place in your veal, surrounded by the veg. Tuck the bay into the veal and pour in the wine and 100ml water.
Bring to the boil, then cover with a circle of greaseproof paper and simmer for 2 to 2 hours 30 minutes, till the veal is tender. Check the liquid level every 20 minutes or so, adding water as necessary.
When the veal is ready, place a frying pan on a medium-high heat with the remaining butter. Tear in the mushrooms and fry until they start to turn golden.
Season, and stir into the veal with the double cream. Bring back to the boil then simmer uncovered for 10 minutes, till reduced.
Transfer the veal to a board and slice. Serve with braised veg, buttered spätzli or noodles and cabbage gratin.