Preheat the oven to 350 degrees f.
Line the bottom of a square 8 inch x 8 inch non stick baking pan with parchment paper.
In a large bowl or stand mixer, combine dry ingredients. Add butter, eggs and vanilla and mix until a soft dough forms. Add Valentines sprinkles.
Spread the dough evenly into the baking pan.
Bake for 15-20 minutes or until a toothpick inserted comes out clean. Allow to completely cool.
Prepare the frosting and decorating ingredients.
Use the back of a spoon or butter knife to spread frosting over the top of the cookie.
Top with Valentine sprinkles and candy hearts.
Cut into 2 inch bars for serving.