Preheat oven to 375 degrees.
Mix cheese, spinach, chicken, onion and 1/4 teaspoon salt for the filling. Set aside.
Dissolve yeast in 1 cup warm wate. Mix yeast mixture, sugar, 1 teaspoon salt, and 1 cup flour in a mixing bowl. Gradually add 1 1/2 cups flour to dough. Knead dough until smooth, use the other 1/2 cup flour if the dough is still sticky.
Roll the dough into a 16 x 10 inch rectange. Spread the filling down the middle of the dough.
Bring the edges of the dough together and seal them. Place seam side down on a lightly greased cookie sheet. Then brush the bread with egg white and sprinkle with the sesame seeds.
Bake at 375 degrees for 40 minutes.
Serve warm or cold and refrigerate.