Preheat the oven to 350°F/180°C. Line a 9×15-inch or 9×13-inch baking pan with parchment paper and set aside.
In a large bowl, whisk together the flour, ginger, baking soda, cinnamon, and salt.
In a separate large bowl or bowl of a stand mixer fitted with a paddle attachment, beat the shortening on low speed and slowly add in the granulated sugar, mixing until fully combined, scraping down the sides of the bowl as needed.
Beat in the eggs one at a time, mixing between each addition, then mix in the molasses until incorporated.
Add the flour mixture a little at a time until fully incorporated.
Transfer the dough to the prepared baking pan and gently press it evenly into the pan.
Bake for 18 to 24 minutes until the edges begin to turn golden and a toothpick inserted into the center comes out clean.
Remove the gingerbread bars from the oven, and allow to cool completely on a wire rack.
To make the frosting, beat together the butter, cream cheese, and vanilla until smooth.
Add the powdered sugar a little at a time and mix until the frosting is smooth.
Spread the frosting over the top of the cooled bars and top with sprinkles.
Slice the bars into squares.
Notes
To Store: Store these bars in the fridge in an airtight container for up to 5 days. Use Extra Parchment: allowing the parchment paper to overflow the edges of the pan will create handles, making it super simple to remove your cooled bars from the pan.Allow to Cool Before Frosting: If you try to frost warm cookie bars, the frosting will melt! Be patient. Cut off the edges: for a really beautiful presentation, cut the edges off of the gingerbread bars before decorating. Save the scraps for snacking later! Choose your pan: I designed this recipe to be baked in a 9 x 15 inch pan, but it will work just fine in a 9 x13 inch pan, your pieces might just be a bit smaller. Make smaller bars: For bite sized treats, slice into smaller squares, or cut each large square in half to make triangles.Add Flavor: For a deeper gingerbread flavor with more molasses notes, substitute 1 cup of light brown sugar for one cup of granulated sugar. Don't wait to add the Sprinkles: Sprinkle the cookie bars right after you frost them so that the sprinkles will stick. If you wait, the frosting will start to harden.