HEAT oven to 350ºF.
TOSS spaghetti and peas with dressing in 9-inch pie plate.
BEAT eggs and milk until well blended; pour over spaghetti mixture. Sprinkle with onions, bacon and cheese; top with tomatoes.
BAKE 40 to 45 min. or until center is set and top is golden brown. Let stand 10 min. before cutting to serve.