In a large saute pan, heat the olive oil. When the oil is hot, add the mushrooms and saute for 3 to 4 minutes. Add the shallots and tomatoes and saute for 2 minutes. Add the garlic and saute for 1 minute. Season with salt and pepper. Add the veal reduction and bring the liquid up to a boil. Reduce to a simmer and reduce the liquid by 1/2, about 4 to 5 minutes. Stir in the truffle oil. Mount in the butter. Using the back of a spoon, gently smash each potato. Season the potatoes with salt and pepper. To assemble, spoon a small pool of the truffle emulsion in the center of each plate. Lay the smash potatoes in the center of the truffle emulsion. Spoon the mushroom stew over each potato. Sprinkle the stew with the grated cheese. Shave the truffles over each plate. Garnish with chives.