Spray a 9-inch baking pan with cooking spray. Line the bottom of the pan with parchment paper and spray the paper lightly with cooking spray. Set pan aside.

Sift together flour, baking powder, salt, and spices in a medium mixing bowl.

In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together until light and fluffy, about two minutes. Scrape down the sides and bottom of the bowl and beat for 30 seconds more. Add egg and vanilla and beat until well combined. Scrape the sides and bottom of the bowl again,

Gradually add the dry ingredients and mix until just combined, taking care to scrape the dough up from the bottom of the bowl so everything is mixed properly. Press the dough into the prepared baking pan and refrigerate for 2 hours.

Preheat oven to 350 degrees. Bake the cookie bars for 14 to 16 minutes, until lightly browned around the edges. Set the pan on a wire rack to cool completely. Once completely cool, run a knife around the edge of the pan, then carefully invert the cookies onto a cutting board.

Combine the cream cheese and butter in the bowl of a stand mixer fitted with the paddle attachment and beat until very creamy. Add the vanilla and salt and beat to combine. Gradually add 1 1/2 cups of the powdered sugar, then turn mixer to high and beat for 3 to 4 minutes. If frosting is too thin, add a bit more powdered sugar to thicken it to your desired consistency. Spread over the cooled cookie bars and top with sprinkles. Slice into bars and serve.