Remove cream cheese and beef tenderloin from  refrigerator one hour prior to cook time. Small dice mushrooms and add them to a preheated sauté pan with 3 tbsp of melted butter and 2 tsp olive oil. Sauté undisturbed in a single layer on medium high for approximately three minutes or until golden brown. Add salt and pepper to taste and toss mushrooms continuing to cook for an additional 5 minutes, stirring frequently to avoid burning. Add chopped chives and stir. Set aside until ready for use. Add 2 tbsp olive oil to your cast iron pan and preheat on high; add the beef. Allow beef to sear undisturbed for 3 minutes, then turn the beef to the other side and continue cooking for an additional 3 minutes for rare, 4 minutes for medium rare. Allow to rest. Slice your bread into 1 inch thick pieces and generously butter one side, then grill butter side down in a sauté pan for 1-2 minutes until golden brown. While the bread is still warm, spread desired amount of cream cheese, then layer mushrooms and sliced filet. Serve and enjoy!