In a large bowl, combine brownie ingredients. Blend with a wooden spoon just until combined. Spread in bottom of baking dish.
For the cookies, beat softened butter with sugar and vanilla until blended. Add egg and combine. Add flour, baking powder and salt and mix until fully combined. Fold in sprinkles.
Drop by spoonful over brownie layer, trying to keep the cookie layer evenly spread.
Bake in a 375 degree preheated oven for 25-28 minutes. Remove and cool completely. Cut and enjoy.
Store in airtight container at room temperature up to 5 days.