Chef John's Creamy Tuna Casserole

Preheat your oven to the optimal temperature for baking, which is 375 degrees F (or 190 degrees C). Next, take a 9x13-inch casserole dish and lightly grease it with butter to prevent sticking.

Melt 3 tablespoons of butter in a medium-sized saucepan over medium heat, stirring occasionally. Once the butter has melted, add sliced onions and sprinkle with a pinch of kosher salt to bring out their natural sweetness. Continue cooking the onions until they start to soften and become translucent, which should take around 3-4 minutes.

Add a tablespoon of all-purpose flour to the saucepan and cook, stirring constantly, for an additional 3 minutes. This step is crucial in creating a smooth sauce. If the heat becomes too intense, reduce it to prevent burning.

Now, slowly pour in a cold glass of milk and whisk the mixture until it's smooth and free of lumps. Increase the heat to medium-high and cook, stirring frequently, until the sauce thickens and reaches a simmering point. Remove from heat and whisk in 1 cup of shredded Cheddar cheese until it's fully incorporated.

Fill a large pot with water and add the remaining salt to bring it to a rolling boil. Cook egg noodles for 5 minutes, or until they're al dente. Drain the noodles thoroughly and transfer them to a large mixing bowl.

Add the reserved sauce, 1 can of tuna, frozen peas, a pinch of cayenne pepper, black pepper to taste, and 1 tablespoon of Worcestershire sauce to the bowl. Mix everything together with a spatula until it's evenly combined.

In a separate small bowl, combine bread crumbs, 1/2 cup of grated Parmigiano-Reggiano cheese, and a drizzle of olive oil. Mix the ingredients together until they resemble wet sand.

Spoon the tuna mixture into the prepared casserole dish and top it with the bread crumb mixture, spreading it evenly to cover the entire surface.

Bake the casserole in the preheated oven for 30 minutes, or until it's golden brown and bubbly. Remove from the oven and let it sit for 10 minutes before cutting and serving.