Melt 3 tablespoons of butter in a large skillet over medium heat.
Add mushrooms and shallots and saute for 4-5 minutes or until mushrooms are softened, making sure that the shallots do not burn.
Add flour and cook for 2 minutes.
Add the sherry and chicken stock to the skillet, 1/2 cup at a time, whisking until combined.
Add House Seasoning Blend; Cook for 10 minutes.
Add cream and cook for 2 minutes more.
Remove skillet from the heat and add remaining tablespoon of butter, whisking until smooth.
Slice filet mignon into thin strips, making sure to slice against the grain of the meat.
Pour sauce over pasta and arrange filet mignon slices on top.