Preheat your oven to 350°F (175°C).

Cream the softened unsalted butter, powdered sugar, granulated sugar, and kosher salt in a mixing bowl until fluffier than a cloud.

Add the vanilla bean paste and egg whites, mixing until everything is velvety smooth.

Incorporate the all-purpose flour gradually, stirring until just incorporated.

Scoop spoonfuls of dough onto a baking sheet lined with parchment paper; space them out. Bake until golden, about 12-15 minutes.

Prepare the whipped ganache by melting the chopped milk chocolate with softened butter, vanilla bean paste, and kosher salt until smooth.

Cool the ganache slightly, then whip until it becomes light and fluffy.

Assemble the cookies by decorating them with the fluffy ganache and adding chopped dark chocolate and colorful sprinkles.