Preheat the oven to 350°F (180°C) and grease a 1-lb (8x4-inch) loaf pan or line with parchment paper. Set aside.
In a medium bowl, whisk together the butter, granulated sugar, light brown sugar, vanilla, molasses, and sour cream until well combined.
Add in the flour, baking soda, cinnamon, ginger, nutmeg, cloves, and salt and use a rubber spatula to fold until just combined. The dough will be very thick.
Once combined, wet your hands slightly (to prevent sticking) and then press the dough evenly into the prepared pan. Bake for 15 to 17 minutes, or until the center is set and no longer jiggles when you shake the pan.
Cool completely in the pan on a wire rack. Once cooled, top with the cream cheese frosting and holiday sprinkles, if using, then slice into bars. Cover and store leftover bars in an airtight container in the fridge for 3 to 4 days.