Asiago Cheese And Italian Sausage Strata

large plain bagels, cut into ½-inch cubes

sweet or hot Italian sausage, cooked and crumbled

shredded Asiago cheese

shredded mozzarella cheese

green onion thinly sliced

whole milk

heavy cream

large eggs, beaten

grated Parmesan cheese

table salt

black pepper, or to taste

ground mustard