Step 1

Preheat oven to 220°C/200°C fan-forced. Lightly grease an 8 cup-capacity ovenproof dish. Cook pasta in a medium saucepan of boiling, salted water, following packet directions, until tender. Drain, reserving 1/4 cup cooking liquid. Return pasta to pan.

Step 2

Melt butter in a saucepan over medium heat. Add flour. Cook, stirring, for 1 minute or until bubbling. Remove from heat. Gradually stir in milk until combined. Return to heat. Cook, stirring constantly, for 3 to 4 minutes or until sauce boils and thickens. Remove from heat. Stir in 1/4 cup cheese. Season with pepper.

Step 3

Add to pasta with tuna and reserved cooking liquid. Toss to combine. Spoon mixture into prepared dish. Sprinkle with remaining cheese. Bake for 12 to 15 minutes or until cheese is melted and golden. Serve.