Cook the pasta: Bring a large pot of salted water to the boil and cook the pasta for 1–2 minutes less than the packet instructions. Drain well and set aside.
Prepare the creamy sauce: Melt butter in a large saucepan over medium heat. Add flour and stir for 1 minute to create a smooth paste. Gradually whisk in the milk, stirring constantly until the sauce thickens and becomes creamy.
Season the sauce: Add chicken stock powder, garlic powder, onion powder, salt, and pepper. Stir through half of the grated cheese until melted and combined.
Combine the filling: Add the drained tuna and frozen peas to the creamy sauce. Stir gently to combine, then add the cooked pasta and mix until everything is evenly coated.
Assemble the pasta bake: Transfer the mixture into a greased baking dish. Sprinkle the remaining cheese over the top and add breadcrumbs if using.
Bake until golden: Bake in a preheated oven at 180°C for 20–25 minutes, or until the cheese is melted, golden, and the pasta bake is heated through.
Rest and serve: Allow the tuna pasta bake to rest for 5–10 minutes before serving. This helps the sauce thicken slightly and makes it easier to portion.
Optional: Serve with a fresh salad, steamed vegetables, or warm crusty bread for a complete family meal.
