This crowd-pleasing breakfast casserole made with Ground Beef, mushrooms and onions can be prepared the night before so the morning is relaxed and easy!
Heat large nonstick skillet over medium heat until hot. Add Ground Beef; cook 8 to 10 minutes, breaking into 3/4-inch crumbles and stirring occasionally. Remove from skillet with slotted spoon; season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Set aside. Pour off drippings from skillet.
Heat oil in same skillet over medium heat until hot. Add mushrooms and onion; cook 3 to 4 minutes or until vegetables are tender, stirring frequently. Return beef to skillet. Add thyme; cook 3 to 5 minutes or until heated through, stirring frequently. Remove from heat. Set aside.
Whisk milk, eggs, remaining 1/2 teaspoon salt and 1/4 teaspoon pepper in large bowl until blended.
Spray 2-1/2 to 3-quart shallow baking dish with nonstick cooking spray. Layer half of the bread cubes, 1/2 cup of the cheese and half of the beef mixture in dish. Pour half of the egg mixture over the top. Top with remaining bread cubes, 1/2 cup of the cheese and remaining beef and egg mixtures. Sprinkle with remaining 1 cup cheese. Press any dry bread cubes into egg mixture. Cover with aluminum foil; refrigerate 6 hours or as long as overnight.
Preheat oven to 350°F. Bake strata, covered, 55 minutes. Remove foil. Bake, uncovered, 10 to 15 minutes or until puffed and lightly browned. Let stand 5 minutes. Top with tomatoes and basil, as desired.
Test Kitchen Tips Cooking times are for fresh or thoroughly thawed Ground Beef. Ground Beef should be cooked to an internal temperature of 160°F. Color is not a reliable indicator of Ground Beef doneness.
To bake strata immediately, heat oven to 350°F. Assemble strata in dish as directed. Bake, covered, 40 minutes. Uncover; bake 10 to 15 minutes or until lightly browned.