1.Cook pasta in a large saucepan of boiling, well-salted water, uncovered, until just tender; drain, return to pan.
2.Meanwhile, melt butter in medium saucepan, add flour, cook, stirring, for about 2 minutes or until mixture thickens and bubbles. Gradually stir in milk, cook, stirring, until sauce boils and thickens. Remove from heat, stir in half the cheeses. Season to taste with salt and freshly ground pepper.
3.Preheat the oven to 220°C(200°C fan-forced).
4.Combine the pasta, chicken, peas, chives and half the sauce; mix well. Spread mixture in a shallow 2 litre (8-cup) ovenproof dish. Spread top with remaining sauce and cheeses. Bake for about 20 minutes or until browned.
Suitable to freeze. Pasta and sauce suitable to microwave.Note