Preheat oven to 350°F and line two cookie sheets with a silicon mat or parchment paper. Place granulated sugar in a shallow bowl and set aside. In a large bowl, combine cake mix, oil, eggs and vanilla extract until there are no large lumps left. Roll 1 heaping tablespoon of dough into balls and coat in granulated sugar. Place on cookie sheets, leaving about 2 inches for spreading. Bake for 9-10 minutes, or until the tops have cracked and the tops look set (the centers will still be gooey). Let sit for 5 minutes and then transfer to a cooling rack. Serve warm or store in an airtight container for up to 5 days.