Preheat oven to 325~. Arrange bread in 15-1/2x10-1/2" jely-rolly pan.
Bake 20 minutes or until crisp. Cool. Meanwhile, brown sausage in
large skillet over medium-high heat; drain on paper towels. Add
onions and thyme to skillet; cook until onion is translucent, about 2
minutes. Remove from heat. Stir in sausage and spinach to combine;
cool completely. Arrange bread in shallow 3-quart baking dish.
Sprinkle 1 cup cheese over top, then layer with sausage mixture and
remaining cheese. Beat eggs, milk, mustard, in bowl until well
blended. Carefully pour into prepared dish; sprinkle top with tomato.
(Can be made ahead. Cover and refrigerate up to 24 hours.) Bake 1
hour or until center is just set. Let stand 10 minutes before
serving. (wrv) until center is just set.