Preheat your oven to 375°F. Bring a large pot of salted water to a boil and cook the egg noodles for about 5 minutes—just until they’re barely tender. Drain and set aside.
While the noodles are doing their thing, melt the butter and add oil in a large skillet over medium heat. Toss in the carrots, celery, onion and season with a little salt and pepper. Cook until the veggies start to soften—about 3 minutes. In the last minute, add the garlic.
Sprinkle in the flour and stir well to coat the veggies. Let that cook for about a minute to get rid of the raw flour taste, then slowly pour in the water, bouillon and heavy cream. Bring the mixture to a gentle boil, then lower the heat and simmer for 2–3 minutes, stirring now and then, until the sauce thickens.
Pour the noodles into your baking dish. Add chicken and corn. Pour the sauce over top and mix well.
In a small bowl, mix together the Panko, Parmesan, and a drizzle of olive oil. Add a pinch of salt and pepper, then sprinkle the topping evenly over the casserole.
Bake for 25–28 minutes, or until the top is golden and crispy and everything is bubbly and delicious.