Step 1

Preheat oven to 350 degrees. Line an 8x8" baking pan with parchment paper or foil, lightly grease, set aside.

Step 2

In a medium size microwave safe bowl (or glass measuring cup), add the butter. Heat until partially melted, then add the white chocolate. Microwave on medium power in 15 second intervals, stirring until melted and smooth. Pour into a large mixing bowl or the bowl of a stand mixer.

Step 3

Add the sugars, eggs and vanilla, mix until combined.

Step 4

In a separate mixing bowl, whisk together the flour, baking powder, and salt. Gradually add to the wet ingredients, mixing just until combined. Fold in sprinkles (and extra chunks of white chocolate if desired) by hand.

Step 5

Pour into prepared pan and place in oven to bake for 25-30 minutes or until top is set and golden brown. Remove from oven and allow to cool in the pan for 45 minutes before removing and slicing.