Vegetable Strata

This is a savory bread pudding, and a great way to use up stale bread of any kind.  I also like to use vegetables that I have cooked for another meal, which is a way of repackaging them without looking exactly like leftovers.  The basic recipe was in the New York Times recently, and I have modified it to use any cooked and seasoned vegetable.  I recently made it with ratatouille, and it was delicious.
1/2 pound stale bread, sliced about 3/4 to 1 inch thick, and cubed
2 c. of sauteed vegetables (mushrooms, onions, garlic, summer squash, roasted tomatoes
1 1/2 cups low-fat milk
2 ounces Gruyère cheese, grated (1/2 cup, tightly packed)
1 ounce Parmesan cheese, grated (1/4 cup, tightly packed)
2 tablespoons extra virgin olive oil
Salt and freshly ground pepper
4 large eggs
1/2 teaspoon salt
Note: If your bread is very hard, carefully saw it into slices with a sturdy serrated knife. Dipping it into the milk for half a minute may help, but this also may cause the bread to crumble as you slice it.
1. If the bread is soft, toast it lightly and rub each slice front and back with the cut clove of garlic. Cut in 1-inch dice. If the bread is stale, just rub the slices with garlic and cut them into 1-inch dice. Place in a very large bowl, and toss with 2/3 cup of the milk. Set aside.
2. Preheat the oven to 350 degrees. Oil or butter a 2-quart baking dish or gratin. 
4. Prepare vegetables--or better yet, use some that you have leftover from another dinner, and transfer to the bowl with the bread cubes. Add the cheeses, and toss together. Arrange in the baking dish.
5. Beat together the eggs in a medium bowl. Add salt to taste (I use 1/2 to 3/4 teaspoon), the remaining milk and the mushroom broth. Add a few twists of the peppermill and pour over the bread. Press the bread down into the custard mixture. Sprinkle a little Parmesan over the top, and drizzle on the remaining olive oil. Place in the oven, and bake 40 to 50 minutes, until puffed and browned. Remove from the oven, and serve hot or warm.