Marinate your mushrooms in melted butter, garlic, and 4 tablespoons sherry for 1 hour.
Cook the pasta according to the package directions in salted water. Then drain and keep 1 1/2 cups of pasta water and set aside.
In a large pot, over medium to low heat, bring your marinated mushrooms to a light sizzle for 3-5 minutes until golden brown.
Gently sprinkle flour over the mushrooms and whisk together to coat. Add in your seasonings and stir constantly for 3 minutes.
Add in the cream and bay leaf, increase the heat to medium and bring your cream mixture to a light simmer. Keep stirring and allow this to thicken up. (8-10 minutes) Then remove the bay leaf.
Reduce the heat to low and add in the mascarpone cheese and stir it all together until well blended and smooth. Then add in your other cheese and gently fold it all together until the cheese is melted.
Now carefully stir in your pasta and 1/2 cup of pasta water. And stir to fully coat it all together.
Option: Add to an oven-safe casserole dish. Top with a panko bread crumb topping, butter, and bake at 400 degrees to lightly brown the top. ( 15 minutes )