In large sauce pot, cook pasta in salted water according to package directions.
Meanwhile, in a small saucepan, combine milk, garlic, nutmeg and chili powder. Bring to a boil; reduce heat; simmer for 5 minutes. When pasta is almost cooked, place in blender the parsley leaves, 1 1/2 cups of the diced avocado, the cheese, lime juice and hot milk with garlic cloves; whirl until smooth. Drain pasta and return to sauce pot. Pour cheese sauce over pasta; toss to combine. Add chives and remaining 1/2 cup diced avocado; toss gently. Serve hot or at room temperature.
