HEAT oven to 350°F.
SPREAD half the bread cubes onto bottom of 13x9-inch baking dish. Top with half each of the onions, bacon, cheddar and mozzarella; cover with cottage cheese. Repeat layers of bread, onions, bacon, cheddar and mozzarella; set aside.
BEAT remaining ingredients with whisk until well blended; pour over ingredients in baking dish. Press bread cubes lightly into egg mixture until completely covered. Let stand 10 min.
BAKE 50 min. to 1 hour or until center is set and top is golden brown.