Preheat Oven to 400 degrees and roughly chop mushrooms and place in oven-safe container. Add olive oil and ¼ C chopped chives.
Place mixture in oven and roast for 20 minutes.
Meanwhile, in a large stock pot, melt the butter, add the flour and mix together. Cook over medium heat for 5 minutes.
Add cracked pepper, salt, and mushroom mixture from the oven.
Mix together, slowly adding beef stock and cook for 10 minutes over medium heat until thickened.
Add heavy cream and stir until combined. Simmer for 15 minutes.
Serve in bowl with garnish of chopped chives and a drizzle of truffle oil.