1 teaspoon active dry yeast
1/4 teaspoon salt
2 cups flour, approximately
1 egg
1/2 cup milk at room temperature
1/4 cup chopped prosciutto
freshly ground black pepper
1 tablespoon oil
Preheat oven to 425F. Dissolve yeast in 2 tablespoons warm water (125F) in a small bowl. Stir in 1 tablespoon flour. Cover bowl with plastic wrap and let sit in a warm place for 1 hour. Put salt and 1-3/4 cup flour in a large mixing bowl. Break the egg in a measuring cup and add enough milk to make 2/3 cup. Add this to the flour, along with yeast mixture. Mix well, adding more flour if necessary, to make a soft dough.
Add the chopped prosciutto and 5 to 6 grindings of pepper. Knead briefly. Oil a 10-inch round pan. Wet hands and press dough into it until entire pan is covered more or less evenly to a thickness of about 1/4-inch. Cover and leave in a warm place 30 minutes. Bake schiacciata 20 minutes, until crust is golden. Cool on a rack and serve slightly warm or at room temperature.