Preheat oven to 350F (175C). Grease a 9x13-inch pan or line with parchment paper. Set aside.
In a large bowl, whisk together butter, sugar, eggs, and vanilla until well-combined.
Whisk in the flour, baking powder, and salt just until combined.
Fold in the chopped chocolate.
Pour the batter into the prepared pan.
Bake until golden brown, about 20-25 minutes. It's better to slighly underbake rather than overbake.
Let the blondies cool in the pan before cutting and serving.
