Preheat the oven to 375°. Place the water and butter in a medium-size saucepan and bring to a boil over medium heat.

Remove the pan from the heat and stir in the flour, bread crumbs, salt, and pepper. Cook over low heat, stirring for 1 minute. Transfer the mixture to a medium-size bowl. Add the eggs, one at a time, mixing well after each addition. Beat in the mozzarella cheese.

Drop the mixture by teaspoonsful on an ungreased baking sheet. Sprinkle with the Parmesan cheese. Bake until puffed and golden brown, about 15 minutes.