Preheat oven to 350℉.
In a medium bowl, combine the flour, baking powder and salt; set aside.
In a stand mixer or a mixing bowl with a handheld beater, beat the softened butter and brown sugar until blended. Add the eggs, one at a time, to the sugar mixture. Add the vanilla and mix well.
Add the flour mixture, half at a time, mixing until just combined. Fold in the chocolate chips.
Lightly grease a 9 x 13-inch baking pan (or line with parchment paper, creasing well along all the corners), and transfer the batter, spreading it evenly.
Bake for 20-25 minutes, give or take depending on oven and color of pan (dark-coated pans cook more quickly), or until the surface is golden and the center is just cooked through. Cool before cutting into bars. Store the cooled bars in an airtight container at room temperature (or in the refrigerator if you prefer them cold). Congo bars freeze well, too.
