Preheat oven to 425°F.
Combine 2 cups flour, undissolved yeast, sugar and salt in a large bowl. Add very warm water and oil; mix until well blended, about 1 minute.
Gradually add enough remaining flour to make a soft dough. Dough should form a ball and will be slightly sticky. Knead** on a floured surface, adding additional flour if necessary, until smooth and elastic, about 4 minutes. Divide dough into 8 portions; cover.
Pat each portion of dough with floured hands into an 8-inch circle on a greased baking sheet. Form a rim by pinching the edge of the dough. Add a second crust to the same baking sheet.
Bake for 6 to 7 minutes, dough will be just set and only lightly browned on the bottom. Remove crusts to a wire rack to cool. Continue with remaining pizza dough. (Works best to use several baking sheets.) May use crusts immediately or place in freezer bags and freeze for up to 1 month. If making a day ahead, place crusts in resealable plastic bags and refrigerate.
When ready to bake, preheat oven to 475°F. Spread each crust with pizza sauce. Top with desired toppings to make Halloween designs! Repeat with remaining pizzas. Place on a baking sheet and bake for 6 to 8 minutes, until cheese is melted and lightly browned and bottom of crust is browned.
*If you don't have a thermometer, water should feel very warm to the touch.
**To knead the dough, add just enough flour to the dough and your hands to keep the dough from sticking. Flatten dough and fold it toward you.Using the heels of your hands, push the dough away with a rolling motion. Rotate dough a quarter turn and repeat the "fold, push and turn" steps. Keep kneading dough until it is smooth and elastic. Use a little more flour if dough becomes too sticky, always working the flour into the ball of dough.