Heat olive oil in a frying pan over medium heat. Add eschalots and gently cook until they begin to brown. Add garlic and mushrooms and cook until tender. Deglaze pan with brandy and season with thyme, parsley, salt and pepper. Remove from heat and allow to cool.
In a large bowl, combine egg, milk, Swiss cheese, cream cheese and pancetta. Fold in mushroom mixture. Spoon evenly into tart shells and place on baking tray.