1. Remove the stems from the mushroom and use them as part of the chopped mushroom mixture, below. Using a tablespoon, scrape out the gills from underneath the mushrooms and discard. Combine all the ingredients for the Portobello mushrooms and toss lightly.
2. In a medium-sized bowl, mix the veal, chopped mushrooms, bread crumbs, milk, garlic powder, onion powder, salt, black pepper and chopped parsley.
3. Form the meat mixture in 4-6 burgers. Reserve for later use.
4. Pre-heat the grill; when hot, grill each mushroom until tender, about 6 minutes and reserve warm. Add the burgers one at a time and brown for 2-3 minutes; turn the burgers over and repeat the browning process, making sure the burgers reach an internal temperature of 160°F.
5. Grill the mushrooms for 3-4 minutes on each side until tender.
6. Add one slice of Swiss cheese to the burgers.
7. Place one Portobello mushroom on a serving platter, add a burger and place the second mushroom on top. Serve immediately.
Nutrition information per serving: 358 k/Cal; 26 g protein; 20 g carbohydrate; 4 g fiber; 20 g fat; 6 g saturated fat; 76 mg cholesterol; 750 mg sodium.