Preheat the oven to 350 degrees.
Prepare a 9 x 13" baking pan with non stick cooking spray and parchment.
In a medium bowl, whisk flour, salt and baking powder. Set aside.
In a mixer fitted with a paddle attachment, cream butter and sugars together. Mix until light and fluffy.
Add eggs and vanilla extract.
On a low speed, add dry ingredients. Mix until just combined.
Stir in sprinkles.
Using a spatula, spread batter into prepared pan.
Bake for 20-25 minutes.
Set on a wire rack to cool.
Once they are cool, remove blondies from pan. Cute off the edges.
Using a ruler, cut blondies into 1 1/2" squares