Preheat the oven to 375 degrees F. Coat a 9-inch pie plate with nonstick cooking spray.
In a large mixing bowl, whisk
together the eggs
, milk, cornstarch
and ground mustard
Stir in the drained tomatoes
, mushrooms, ham and scallions. Season liberally with salt and pepper. Stir in the croutons before transferring the mixture to the prepared pie plate
. Top with the Cheddar
Bake until the center is set, about 30 to 35 minutes. Let cool on a wire rack. Serve warm or at room temperature.