
Preheat oven to 350F. Butter 13x9x2-inch glass
baking dish. Cook
pasta in large pot of boiling salted water until
tender but still
firm to bite, stirring occasionally, about 8 minutes.
Drain.
Meanwhile, melt butter in heavy large saucepan
over medium-low heat.
Add flour. Cook 1 minute, stirring constantly (do
not allow to
brown). Gradually whisk in milk and cream. Simmer
until mixture
thickens slightly, whisking occasionally, about
3 minutes. Reduce
heat to low. Add grated cheddar cheese and 1 cup
crumbled blue
cheese. Whisk until cheese melts, about 2 minutes.
Season sauce to
taste with salt and pepper.
Add cooked pasta to sauce; stir to coat. Transfer
mixture to
prepared baking dish. Sprinkle with remaining 1/2
cup blue cheese.
Bake until sauce begins to bubble, about 25 minutes.
Sprinkle with
chives and serve.
