Preheat your oven to 350°F (175°C).
Cook the egg noodles according to package instructions; drain and set aside.
In a large bowl, mix the cream of mushroom soup with milk until smooth.
Add the drained tuna, frozen peas, chopped onion, and cooked noodles to the soup mixture.
Stir in half of the shredded cheddar cheese and season with salt and pepper.
Transfer the mixture to a greased baking dish.
Top with the remaining cheddar cheese and breadcrumbs.
Drizzle olive oil over the breadcrumbs for extra crunch.
Bake in the preheated oven for 25-30 minutes or until golden and bubbling.
Let it cool for a few minutes before serving.