Preheat the Oven: Preheat the oven to 350°F (175°C) and grease or line a 9x13-inch baking pan.
Prepare the Dough: Whisk together flour, baking powder, baking soda, and salt in a bowl. Cream together butter and sugar in a separate bowl until light and fluffy. Add eggs, vanilla, and sour cream; mix until combined.
Combine: Gradually add the dry ingredients into the wet mixture, stirring until just combined.
Bake: Spread the dough evenly into the pan and bake for 20-25 minutes until golden. Let it cool completely.
Make the Frosting: Beat together butter, powdered sugar, vanilla, and cream. Add food coloring and mix until smooth.
Frost and Decorate: Spread frosting over the cooled bars and decorate with sprinkles or heart-shaped candies.
Serve and Enjoy: Cut into squares and serve!