Preheat oven to 425 degrees.
Open pizza dough and spread out on a large, flat surface, dusted with flour.
Roll pizza dough into a 16" x 16" square (older kids can help here).
Trim edges to get rid of uneven sides. Then cut the large square into 16 4" x 4" squares.
Mix cheese and ½ cup of your choice of extra ingredients in a bowl. Your combination of fillings/cheese should be equal to one cup. If you'd like, you can simply use one full cup of shredded cheese.
Place a tablespoon of filling mixture in the center of each dough square.
With each dough square, fold one corner over to touch the opposite corner, making a triangle "pocket" with the filling inside. Press edges down firmly, and transfer to a greased baking sheet.
Use a fork to firmly crimp the sealed edges of each filled pocket (again, older kids love to help here).
Brush each pocket with the beaten egg mixture (now the littler kids get a turn to help).
Bake for 8-10 minutes. The pockets are ready when they're golden brown on top. Some cheese might escape out the side, but even that cheese is tasty.
Cool and serve with optional ranch.