Preheat your oven to 350 degrees Fahrenheit and prepare a 9 by 13 inch baking dish with cooking spray or parchment paper.

In a medium bowl, whisk together the flour, baking powder, and salt, then set aside.

In a large mixing bowl, cream together the room-temperature butter and sugar on medium speed until light and fluffy, about 3 to 6 minutes.

Add eggs one at a time, mixing well after each addition, then mix in the vanilla extract.

Gradually mix the flour mixture into the wet ingredients on low speed until combined.

Gently press the cookie dough into the prepared baking dish and bake for 25 to 27 minutes until the edges are golden brown.

Let the cookie bars cool for an hour.

In a medium bowl, beat the room-temperature butter and 1 cup of powdered sugar until well blended.

Mix in the milk and vanilla extract, then gradually add more powdered sugar until you achieve a creamy consistency. Add red food coloring to your desired shade.

Frost the cooled cookie bars and top with sprinkles.

Cut into 24 equal squares and store in a single layer.