Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.
In a large bowl, combine the melted butter and brown sugar.
Add eggs and vanilla extract; mix until smooth.
In a separate bowl, whisk together flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the chocolate chips.
Pour the batter into the prepared baking pan.
Smooth the top with a spatula.
Bake for 20-25 minutes or until the edges are golden brown.
Allow to cool before cutting into squares and serving.