Begin by bringing a large pot of water to a rolling boil. Add the udon noodles carefully, cooking until al dente, about 6-8 minutes. Reserve at least one cup of pasta water, then drain the noodles and set aside.

In a large skillet, heat 2 tablespoons of olive oil over medium-high heat. Add sliced mushrooms and sear them undisturbed for 5-7 minutes until golden brown.

Reduce heat to medium and add 2 tablespoons of butter, along with minced garlic and finely diced shallot. Sauté for about 2 minutes until fragrant.

Pour in 1 cup of heavy cream, along with reserved pasta water, and add 3 tablespoons of miso paste. Stir well and let simmer for 2-3 minutes.

Gently toss the cooked udon noodles into the sauce, ensuring every strand is well coated. Adjust thickness with reserved pasta water as needed and stir in Parmesan cheese.

Serve hot, plating the noodles and drizzling remaining sauce on top, garnished with chopped nori and red pepper flakes.