Preheat the oven to 350°F (175°C) and generously grease a 9- or 10-inch tube or Bundt pan.
Combine white sugar and cinnamon in a large plastic bag. Cut the biscuits into quarters, add 6–8 pieces at a time to the bag, and shake until evenly coated.
Arrange the coated biscuit pieces in the prepared pan, layering as you go. If using walnuts and raisins, scatter them among the biscuit pieces evenly.
In a small saucepan over medium heat, melt the butter and brown sugar together. Bring to a boil and cook for 1 minute, then pour the mixture evenly over the biscuits.
Bake for 35 minutes, until golden and bubbly. Let cool in the pan for 10 minutes, then invert onto a serving plate. Serve warm and pull apart to enjoy.