Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a stand mixer, beat together the room temperature butter, granulated sugar, and brown sugar until smooth.

Add the eggs and vanilla bean paste (or vanilla extract), mixing until well combined.

Gradually add the all-purpose flour, baking powder, and kosher salt while mixing until the dough is fully blended.

Gently fold in the rainbow sprinkles with a spatula.

Scoop half of the dough and shape it into a rectangle on the prepared baking sheet. Repeat with the remaining dough.

Chill the shaped dough in the fridge for 20 minutes.

Bake the biscotti in the preheated oven for 20-30 minutes or until the tops are golden brown.

Allow the biscotti to cool on the baking sheet for about 25-30 minutes.

Reduce the oven temperature to 325°F (163°C). Slice the biscotti into individual pieces and place them back on the baking sheet.

Bake again for 25-30 minutes until they are dry and golden.

Once baked, allow the biscotti to cool on a wire rack. Drizzle with melted white chocolate and allow to harden before storing.