Preheat the oven to 350 degrees F and lightly grease a 9X13 baking pan.

To Make the Cookie Bars: In a large bowl, cream together the butter and sugar until well combined and light and fluffy.  Then add in the eggs and the vanilla extract.  Mix for 1-2 minutes until they are incorporated.

Then hand stir in the flour, baking powder and salt.  Stir until just combined, being careful not to over mix.

Then spread the dough into the 9X13 pan and press the dough down slightly.  Bake for 10-13 minutes.  Be careful not to over bake.  The middle should be just set and the edges should have a very slight color on them.  Then move the pan to a wire rack to allow the bars to cool completely.

To Make the Frosting: Cream together the butter and powdered sugar until combined and smooth.  Then add in the milk and vanilla extract and mix for 1-2 minutes until the frosting is light and fluffy.  Then dye the frosting with food color (optional).

Spread the frosting on top of the cooled cookie bar and top with the sprinkles (optional).

Then the bars are ready to slice, serve and enjoy!