Boil noodles according to directions.
Chop onions, carrots, and peppers.
Saute vegetables in butter with a drizzle of olive oil.
Sprinkle 1/4 c AP flour over vegetables, then immediately whisk in cream until smooth and thick.
Combine Bechamel sauce in a bowl with tuna and noodles and cheese.
Spread in a large baking dish. Sprinkle with cheese.
Bake at 350* for about 30-45 minutes, depending on how crispy you like the top.