1. Preheat oven to 475°F.
2. Fill a pot with 10 cups of water and bring to a boil. Season with salt.
3. Clean mushrooms with brush to remove dirt.
4. Combine mushrooms with chopped tarragon and olive oil to coat. Place mushrooms
in oven proof pan large enough to hold mushrooms in a single layer. Place in oven
and cook for approximately 20-25 minutes. Mushrooms should reduce in size giving
off liquid. Remove from oven. DO NOT DRAIN!
5. Reduce heat in oven to 375°F.
6. Make roux. In a separate pot, melt 4 tbsp. butter over medium heat. Add flour and
stir well. Cook, stirring to remove any lumps.
7. Add cold milk, 1/2 cup at a time, stirring to remove any lumps before adding more
milk. Once all of the milk is incorporated and sauce is hot, slowly stir in shredded
cheese 1/2 cup at a time until all is incorporated and sauce is smooth. Whisk in Dijon
Mustard.
8. Add roasted mushrooms and cooking liquid to the cheese sauce, stir well. Adjust
seasoning with salt and pepper.
9. Melt remaining 2 tbsp. butter, combine with Panko Bread Crumbs and chopped
parsley. Reserve until needed.
10. Add pasta to boiling water and cook according to directions, 10-12 minutes.
11. Drain pasta. In a large bowl, combine hot drained pasta and cheese/mushroom sauce.
Stir to coat pasta well.
12. Place pasta in a sprayed casserole dish. Top with buttered Panko.
13. Place in 375°F oven. Cook for 40 minutes, uncovered.