Chicken Tetrazzini with Mushrooms and Sherry

Name: Chicken Tetrazzini with Mushrooms and Sherry
Ingredients: Kosher salt; 1/2 cup unsalted butter; 2 teaspoons dried French thyme; 1 large shallot, finely chopped; 2 cups sliced button mushrooms; 3/4 cup sherry; Freshly ground black pepper; 2 pounds spaghetti; Nonstick cooking spray; 1 cup unsalted butter, plus 1/2 cup melted butter; 1/2 cup all-purpose flour; 3 1/2 cups half-and-half; Salt and freshly ground black pepper; 10 cups shredded cooked chicken; 3 cups shredded white Cheddar; 2 cups fresh breadcrumbs; Smoked paprika, for dusting