Line a 13x9 baking dish with parchment paper, leaving extra on the ends to use as handles to remove bars easily.
In a medium bowl, whisk together the dry ingredients: flour, cinnamon, baking soda, ginger, nutmeg, cloves, and salt.
In a large bowl, cream together the butter and both sugars until light and fluffy, about 3 minutes. Add molasses, eggs, and vanilla and beat until well combined.
Now add the sifted flour mixture and mix until well combined.
Press dough into the prepared baking dish. Make sure to press it well into the corners of the baking pan, using your fingers, too.
Bake for 15-18 minutes, but do not overbake.
Cool in the baking pan on a wire rack for about 10 minutes.
Only then lift the parchment paper with the gingerbread cookie base from the pan and place it on a wire rack to cool completely.
Frosting
In the meantime sift powdered sugar. This step is optional, but it makes the frosting creamier.
Cream together butter and cream cheese with a fork until smooth. Beat in clear vanilla extract using a whisk and mix well.
Gradually add the sifted powdered sugar until well combined and the frosting is the desired consistency. It should become a fluffy cream cheese frosting.
Frost the cooled gingerbread base evenly, using a spatula. Decorate the bars with sprinkles or candy of your choice.
Cut into bars and serve, or store in an airtight container for up to one week.
Notes
Vanilla: Using clear vanilla extract in the frosting will keep the frosting white.