Preheat oven to 425 Degrees F.
1. Heat 1 tablespoon butter in a large, heavy nonstick skillet over medium-high heat until hot. Add the mushrooms and salt and pepper to taste. Cook, stirring occasionally, until browned, about 7 minutes. Remove from pan and set aside.
2. Wipe out the skillet. Heat the ghee in the skillet over medium high heat until hot. Place fillets in pan, it will sizzle and make you feel like a professional chef. Sear until nicely browned. Flip the fillets and place in preheated oven for 15 minutes. Remove from oven and pan and cover loosely with foil.
3. Add the shallots to the same skillet and cook over medium heat, stirring, until golden, about 3 minutes. Add the mustard and white wine and bring to a boil, stirring often and cooking until reduced by half. Stir in the last tablespoon butter. Spoon the sauce on a plate; place the beef on the sauce and spoon the mushrooms over the top. Garnish with chives and serve!