TOPPING : Combine brown sugar, butter and cream in a medium-heavy saucepan set over medium heat. Cook, stirring, just until melted and smooth. Pour into a buttered 9 x 13-inch baking pan. Sprinkle with pecan halves.
Preheat oven to 400°F (200°C). Stir flour with granulated sugar, baking powder, baking soda and salt in a large bowl. Use a box grater to grate in butter; stir to combine. Stir in buttermilk until dough starts to cling together (it will be dry). Turn onto a lightly floured surface; knead a few times to bring dough together. Pat or roll into a large rectangle, about ½ inch thick.
FILLING : Blend brown sugar with butter and cinnamon; spread evenly over dough. Sprinkle with chopped pecans. Starting at wide end, roll into a log. Cut into 12 portions; arrange, cut side up, over topping.
BAKING : Bake, on centre rack, for 20 to 22 minutes or until biscuit sounds hollow when tapped. Let cool for 5 minutes in pan, then carefully turn out onto a tray to serve.