First...
Preheat the oven to 350°F. Take a 13x9-inch baking pan, grease the inside of it, and then set it aside.
Next...
Melt the butter in a microwave-safe bowl just long enough for it to melt. Stir in the sugar and vanilla, and then beat in the eggs. Add the cocoa powder, flour, baking powder, salt, and both types of chocolate chips to the batter, and then beat until well combined.
Last...
Pour the batter into the baking pan and bake for about 30 minutes (or less if you used a smaller pan). They are done as soon as they start pulling away from the sides of the pan. Let it cool to room temperature, then remove from the pan, cut into squares and enjoy!