Preheat oven to 350 ºF. Butter 13x9x2 inch ceramic or glass baking dish. Whisk first 7 ingredients in large bowl; sprinkle generously with pepper. Set aside.
Place sausage in large nonstick skillet; push to 1 side. Add bell pepper to other side of skillet. Sauté acute; over high heat, breaking up sausage with fork, until sausage is cooked through and bell peppers are brown in spots, about 7 minutes.
Arrange half of bread slices in prepared dish. Pour half of egg mixture over. Sprinkle with half of cheese, then half of sausage-pepper mixture. Repeat layering. Refrigerate overnight, occasionally pressing on bread to submerge. Bake strata until puffed and brown, about 1 hour. Cool slightly.