Make Gingerbread Cookie Bars:

1. Preheat oven to 350°F (175°C) and grease a 9×13-inch jelly roll pan with non-stick cooking spray. Set aside.
2. In a large bowl, whisk together the flour, baking soda, cinnamon, ginger, nutmeg, cloves, and salt. Set aside.
3. In the bowl of a stand mixer or using handheld beaters, cream together the melted butter, granulated sugar, brown sugar, vanilla, and molasses on medium speed until light and fluffy, about 2-3 minutes.
4. Add the egg and mix until fully combined. Gradually add the dry ingredients, mixing on low until the flour is incorporated, then increase the speed to medium and mix for 1 minute.
5. Spread the dough evenly into the prepared pan and bake for 15-20 minutes, or until the bars are a darker color and a toothpick inserted comes out with a few moist crumbs. Move the pan to a wire rack and allow the bars to cool completely before frosting.

Make Cream Cheese Frosting:

1. In a clean mixing bowl, cream together the softened cream cheese and butter on medium speed until light and fluffy, about 2-3 minutes.
2. Add the powdered sugar and vanilla extract, and pulse to combine. Then, increase the speed to medium-high and mix until creamy and smooth, about 1-2 minutes.

To Finish:

1. Once the cookie bars are completely cooled, frost them with the cream cheese frosting. Add holiday sprinkles if desired.
2. Slice the bars into 24 pieces and serve.