Preheat oven to 350°F. Lightly grease a 9x13 baking pan with cooking spray. Set aside.
In a medium bowl, whisk the flour, baking powder, baking soda, ginger, cinnamon, nutmeg, cloves, and salt. Set aside.
In a large bowl, beat butter, brown sugar, and granulated sugar until smooth and fluffy with an electric hand mixer or stand mixer with fitted paddle attachment, about 2-3 minutes. Add egg and molasses and beat until combined.
Gradually add flour mixture to wet mixture and beat until combined.
Press batter evenly onto the bottom of prepared pan. Bake for 15-20 minutes, or until edges are set and center is just slightly underbaked. Let cool completely in pan before frosting and/or cutting into bars. **For bars that are chewy, be sure to keep an eye on your oven at the 15-minute mark. You want the center to be just slightly underbaked, as it will continue to firm up when cooling**
To make the cream cheese frosting, beat cream cheese and butter until smooth and creamy. Add powdered sugar and vanilla and beat until fluffy. Spread over cooled bars and cut into squares. Top with holiday sprinkles, if desired.