In 1-quart saucepan melt butter; saute onion and green pepper.
Remove from heat; stir in soup and sour cream.
In buttered 2-quart casserole layer 1/3 of the noodles, 1/3 of the Swiss cheese, 1/3 of the ham and 1/2 soup mixture.
Repeat layers, ending with final 1/3 layer of noodles, cheese and ham.
Bake in preheated 350°F oven 30 to 45 minutes or until heated through.