Mix together sugar, salt, milk, and oil. Add 1 cup of flour and mix. Add yeast mixture and then enough flour to make a light dough. Add one cup of flour at a time, so that the dough is "more thick than thin; enough so it doesn't stick to your fingers". Work the dough until it's nice and elastic and smooth.
Place dough in a warm crock or bowl: cover and let rise in warm place until double in bulk, about 30-40 minutes.
To prepare filling: open cans of filling into a mixing bowl. Add graham cracker crumbs. (The filling is expensive, and the crumbs act as a filler to stretch the filling. Alternately, you could use another can of filling.) Mix until crumbs are incorporated into the filling.
Punch down dough; oil hands and make into walnut-sized balls. Place on greased cookie sheets. Cover and let rise in a warm place until light, about 10 minutes. Make a large indentation with fingers, pushing out the sides of the ball with fingers and fill with filling and sprinkle on topping. Cover and return to warm place to let rise again, about 10 minutes.
Bake in preheated 400 oven until lightly golden, about 10-12 minutes. Cool on sheet. Optional: When you remove from oven, brush the crusts with margarine.