Spinach, Veggie and Cheese Strata

1 tablespoon butter or margarine
1 box (9 oz) frozen spinach, thawed, squeezed to drain
2 medium red bell peppers, cut into strips (or any color besides green pepper)
1 cup sliced leeks
2 cups shredded sharp cheddar cheese
1 loaf (9 oz) ciabatta or French bread, cut into 1-inch cubes (6 cups)**
7 eggs
1 1/2 cups milk
1 tablespoon Dijon mustard
1/2 teaspoon pepper

Spray 13x9-inch (3-quart) glass baking dish with cooking spray. In 10-inch skillet, melt butter over medium-high heat. Add spinach, bell peppers and leeks; cook 4 to 5 minutes, stirring frequently, until crisp-tender. Remove from heat. In baking dish, spinach mixture, 1 cup of the Cheddar cheese and the bread. In large bowl, beat eggs, milk, mustard and pepper with wire whisk until blended; pour over bread. Sprinkle with remaining Cheddar cheese. Cover with foil; refrigerate at least 4 hours but no longer than 24 hours.

Oven at 325°F. Bake loosely covered 40 minutes. Uncover; bake about 30 minutes longer or until top is golden brown and knife inserted in center comes out clean.

**Note-In my family we save the bread ends in the freezer to use later for french toast. They also make a great substitution for the french bread loaf in this recipe.
**Note-You may also add several cups of chopped ham to the spinach mixture for a yummy addition.