How to Make It
Preheat the oven to 375°. In a medium roasting pan, rub the turkey drumsticks with the vegetable oil and season with salt and pepper. Roast the turkey for about 45 minutes, until cooked through. Let stand until cool enough to handle, about 10 minutes. Cut the turkey meat into 1/2-inch pieces; discard the skin and bones.
Bring a large pot of salted water to a boil. Add the rotini and cook until it is al dente. Drain the pasta well.
Meanwhile, in a large, deep skillet, melt 1 stick of the butter. Add the diced shallots and cook over moderate heat until softened, about 4 minutes. Add the shiitake and oyster mushrooms and cook until softened, about 5 minutes. Add the sage and thyme and cook until fragrant. Add the wine, bring to a boil and cook over high heat until reduced by half, about 3 minutes. Add the flour and cook over moderate heat, stirring constantly, until moistened, about 1 minute. Add the chicken stock, bring to a simmer and cook over low heat until thickened, about 3 minutes. Stir in the cream, turkey, peas and pasta and season with salt and pepper.
Spread the contents of the skillet in a deep, 9-by-13-inch baking dish.
In a medium microwave-safe bowl, melt the remaining 2 tablespoons of butter. In a food processor, pulse the bread until fine crumbs form. Add the bread crumbs and Parmigiano-Reggiano cheese to the melted butter and toss. Season the bread crumbs with salt and pepper and sprinkle evenly over the casserole. Bake the casserole for about 30 minutes, until golden brown on top. Serve hot.