Coat a 9-by-13-inch baking dish (or similar shallow 3-quart baking dish) with cooking spray.
Cook sausage in a large nonstick skillet over medium heat, crumbling with a wooden spoon, until lightly browned, 3 to 4 minutes. Transfer to a plate lined with paper towels to drain. Add onions and bell pepper to the pan and cook, stirring often, until softened, 3 to 4 minutes.
Whisk eggs, milk, salt and pepper in a large bowl until blended.
Spread bread in the prepared baking dish. Scatter the sausage and the onion mixture evenly over the bread. Brush with mustard. Sprinkle with cheese. Pour in the egg mixture. Cover with plastic wrap and refrigerate for at least 2 hours or overnight.
Preheat oven to 350 degrees F. Bake the strata, uncovered, until puffed, lightly browned and set in the center, 55 to 65 minutes. Let cool for about 5 minutes before serving hot.
Per serving :
13 g Fat;
45 g Sat;
4 g Mono;
229 mg Cholesterol;
19 g Carbohydrates;
17 g Protein;
2 g Fiber;
513 mg Sodium;
380 mg Potassium
1 Carbohydrate Serving
Exchanges: 2/3 starch, 1/3 milk, 1/2 vegetable, 1 very lean protein, 1 1/3 medium-fat protein
Tips & Notes
Make Ahead Tip: Prepare through Step 4 the night before serving.