Preheat oven to 350°.
Toss grated cheddar cheese with flour.
Place in ungreased casserole (8" squre or pie plate).
Sprinkle grated jack cheese over top.
Combine half & half and eggs, add Worcestershire sauce, mix well, and pour over cheeses.
Sprinkle chopped tomato and basil over egg mixture and bake for 35 to 40 minutes.
Can be prepared 24 hours in advance of baking.
Serves six to eight.