Preheat oven to 350 degrees
Lightly grease a 9x13 pan
In a large bowl, mix together melted butter and brown sugars
Whisk in 2 eggs and vanilla extract
In another medium bowl, shift together flour, baking powder, baking soda, and salt
Gently fold dry ingredients in with wet ingredients, just enough to combine
Add and fold in chips
Scoop batter (it is thick) into 9x13 pan and spread to the edges of the pan
Bake for 30 minutes or until toothpick inserted comes out clean (a few crumbs are okay but not wet)
Cool for 5 minutes before cutting to serve
Store any remaining blondies in an airtight container for 2 to 3 days