Preheat oven to 425 degrees F.
Sift together the flour, sugars, baking soda, and salt. Making sure the butter is cold, cut it into the dry mix until it becomes crumbly. Add half-and-half until the mixture is just moistened. Fold in the cranberries.
Pour out the batter on a floured surface and knead slightly. The dough should be stiff and able to hold its own shape. It is ok if it is a little crumbly. Pound the dough into a 1-inch thick circle. (Use a very small amount of half-and-half if you need the dough to hold together more.) Slice the dough into 8 triangles and place on a baking sheet. Sprinkle sugar and cinnamon on top if desired. Bake for 12-15 minutes.