Make this savory bread pudding the night before serving and you’ll be able to feed a crowd for holiday brunch.
Generously grease a 9x13-inch baking dish with softened butter. Fit 6 bread slices into the dish. (Don’t worry if there are spaces; as the bread soaks, it will swell to fit.)
In a large bowl combine ricotta, Parmesan, ham, and rosemary. Spread half the mixture on top of the bread layer and smooth with a spoon. Add a second layer of bread and cover with remaining mixture. Add a final layer of bread.
In a bowl combine milk and eggs. Whisk until smooth, and pour over strata. Cover dish with aluminum foil or plastic wrap, and refrigerate overnight.
Remove chilled strata from refrigerator at least a half hour before baking and set out at room temperature. Bring a kettle of water to boil over high heat.
Preheat oven to 350°. Remove wrapping from strata and sprinkle grated cheddar over strata. Place the baking dish inside a larger roasting pan, and carefully pour in enough hot water to come halfway up the sides of the strata pan.
Bake until puffy and brown and a knife inserted into the center comes out clean, about 1 hour. Cool 20 minutes, cut into squares, and serve.