Preheat the oven to 425ºF. Lightly grease a large baking sheet.
In a large bowl, stir together the flour, sugar, baking powder, ½ teaspoon of salt, and pumpkin pie spice. Cut in the cold butter with a fork or pastry tool until the mixture resembles coarse crumbs. Add the carrots and ⅔ cup of buttermilk and stir just until combined.
Turn the dough out onto a lightly floured surface. Sprinkle the dough with the raisins. Knead 10 times. Roll the dough to approximately a 1-inch thickness. Using a 2-½-inch round cutter, press out biscuits, rerolling the dough as necessary.
Place the biscuits on the prepared baking sheet at least 1 inch apart. Bake for 20 minutes, or until golden brown. Brush the tops with the remaining buttermilk. Set aside.
In a bowl, beat together the softened butter, caramel sauce, and remaining salt until combined. Serve with the biscuits.