For a simpler approach, use chestnut mushrooms for the duxelle and blend them.
To elevate the dish, use shiitake and chestnut mushrooms, finely chop them instead of blending, and sauté with thyme, shallots, garlic, and flambé with whiskey.
Make homemade crepes to combat potential soggy bottoms.
Use a meat thermometer to ensure the beef is cooked to your desired doneness.