Ingredients:

  • 1 cup unsalted butter, softened
  • 1.5 cups granulated white sugar
  • 1 large egg, room temperature
  • 2 tsp pure vanilla extract
  • 2.25 cups all-purpose flour
  • 1 tsp baking powder
  • 0.5 tsp salt
  • 2 cups powdered sugar, sifted
  • 3 tbsp heavy cream
  • 1 tsp pure vanilla extract
  • 0.25 cup rainbow sprinkles

Instructions:

  1. Preheat the oven to 350°F (175°C). Line a 9x13 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
  2. Beat the softened butter and granulated sugar on medium-high speed for approximately 3 minutes until the mixture is pale and fluffy.
  3. Mix in the egg and vanilla extract until the mixture is fully emulsified.
  4. Reduce mixer speed to low. Gradually add the flour, baking powder, and salt, mixing only until the flour streaks disappear to avoid overmixing.
  5. Press the dough evenly into the prepared baking pan using a spatula.
  6. Bake for 18–22 minutes. Remove from the oven when the edges are barely golden and the center still appears slightly underdone.
  7. Allow the bars to cool completely. While cooling, whisk together the powdered sugar, heavy cream, and vanilla extract until smooth.
  8. Pour the icing over the cooled bars, spread evenly, and immediately top with rainbow sprinkles.