Lobster Macaroni And Cheese

Heat oven to 375. Bring a 4 qt saucepan of salted water to a boil. Add pasta and cook, stirring occasionally, until cooked half way through, about 3 min. Drain pasta, transfer to a bowl, and set aside.
Melt butter in a 4 qt saucepan over med. heat. Add flour and cook, whisking constantly, until smooth, about 1 min. Whisk in milk and cook, continuing to whisk often, until sauce has thickened and coats the back of a spoon, about 10 min. Remove pan from heat and stir in 2 c fontina, along with the mascarpone, broth, brandy, tabasco, and nutmeg: season wit salt and pepper. Add reserved pasta to cheese sauce. Stir in half each of the lobster, chives, and scallions. Transfer mixture to a 9X13 baking dish and sprinkle with remaining fontina and the cheddar. Bake until golden brown and bubbly, about 30 min. Let cool 10 min, and garnish with remaining lobster, scallions, and chives.