Preheat your oven to 350°F (175°C) and prepare two baking sheets by lining them with parchment paper.

In a large mixing bowl, combine softened unsalted butter, granulated sugar, and light brown sugar. Beat on medium speed for about 2-3 minutes until light and fluffy.

Add the large eggs one at a time, mixing well after each addition, then blend in the cake batter extract.

In a separate bowl, whisk together the baking powder, salt, and all-purpose flour. Gradually add to the wet ingredients, mixing on low speed until just combined.

Gently fold in the rainbow sprinkles using a spatula until evenly distributed.

Drop dollops of dough onto prepared baking sheets, spacing them about 2 inches apart. Flatten each dough ball slightly.

Bake in the preheated oven for 13-16 minutes until edges are golden and centers are soft.

Allow cookies to cool on baking sheets for 5 minutes before transferring to a wire rack for complete cooling.

Beat softened butter with powdered sugar in a mixing bowl. Gradually add cake batter extract and whipping cream until desired fluffiness is reached.

Once cookies are cool, frost each cookie generously and top with additional rainbow sprinkles.