Sauteed Mushrooms:

1. Heat a large cast iron skillet to medium-high heat. Add butter, shitake mushrooms and baby bella mushrooms and saute for 3-5 minutes, stirring occasionally. 
2. After 5 minutes, season with salt and pepper (this keeps the mushrooms from browning too early). Stir and cook an additional 2-3 minutes or until mushrooms are slightly browned. Set aside.

Cast Iron Filet:

1. Allow steaks to sit on the counter 30 minutes prior to cooking to “take the chill off.”
2. Generously season both sides with salt and pepper.
3. Preheat oven to 400°F.
4. Heat a large cast iron skillet to high heat. Add butter to the pan and immediately add seasoned steaks. Sear for 2 minutes and flip. Then add garlic cloves and thyme to the cast iron, sear the other side for 2 minutes – spooning butter over the top of the steaks throughout.
5. Transfer the skillet, uncovered, to the oven and cook steaks for 5-6 minutes for medium rare, 7-8 minutes for medium, 8-9 minutes for medium-well and 10-11 minutes for well. Cooking times are not exact, it will depend on the thickness of your steak. If your steak is thick it will be longer, if your steak is thin it will need less cook time. A good way to be sure is to use a meat thermometer –  120°F to 125°F is medium rare.
6. Remove steaks from the oven and let rest for 5 minutes.

Mustard Cream Sauce:

1. Heat a medium skillet to medium-high heat. Add butter, shallots and garlic. Saute for 2-3 minutes, until shallots are translucent. Season with salt and pepper. 
2. Next, add heavy cream, dijon mustard, stone ground mustard and fresh thyme. Whisk together to combine and bring to a slow simmer for about 2-3 minutes. If the mixture is too thick, add 1-2 tablespoons of water to thin it out. Set aside.

Assemble Steaks:

1. Once steak have rested, top with pan seared mushrooms and mustard cream sauce. Serve.