Pre-heat oven to 180°C / 360°F
Cook spaghetti for one minute less than specified on the packet. Drain pasta and add it to the bottom of large baking dishes.
In a large pan, combine the Butter with Flour and Milk. Heat on medium-high. Continue whisking the sauce until it has thickened and the butter is completely melted (around 3 minutes). Whipping will stop lumps from forming and give you a smooth, white sauce!
Add the delicious cheese, parmesan and chicken stock. Optionally, add nutmeg, salt and pepper.
Stir in the corn and peas. The tuna can be added and broken up with a whisk. You can make the chunks as big or as small as you want. Continue whisking until all ingredients are well blended. Let the mixture heat for about a minute, and then turn off the heat.
Mix the sauce with the pasta in a baking dish.
Spread the top of the omelette with the back side of a wooden spoon. Sprinkle with cheese and breadcrumbs. Bake for 15-20 minutes, or until golden brown.