Preheat oven to 400 degrees. Combine four dinner rolls and roll out onto a lightly floured surface into a medium circle. The dough might pull back at first, but just keep rolling. Repeat with remaining four dinner rolls. The dough does puff up quite a bit while baking, so roll out fairly thin. Place medium pizzas onto a large greased baking sheet. Top each pizza with 1/3 cup of pie filling. I chose to puree my pie filling, but that is completely optional. Next, make the streusel topping. In a small bowl, combine brown sugar, flour, cinnamon, salt and unsalted butter. Using your clean hands, rub the ingredients together until it resembles wet sand. Sprinkle evenly over pizzas.
Place in preheated oven and bake for 10-15 minutes or until bottom is browned and top is bubbly. If air bubbles start to form while baking, you can pop them using a toothpick. Remove from oven and allow to cool. Meanwhile, place frosting into a piping bag that has been fitted with a round tip (I used a Wilton #12 tip). Once the pizza has cooled, pipe three to four circles onto pizza, starting with a small circle in the center and then working out from there. Take a toothpick and starting with the center circle, drag the toothpick to the outer edge. Continue around entire pizza. Top with plastic spiders. Slice and serve.