Preheat oven to 350 degrees. Lightly grease an 8 by 8 inch baking pan.
In a large microwave safe bowl, add the chocolate chips, vegan butter (or coconut oil) and cocoa. Melt in the microwave in 30 second increments until mostly melted, and stir well at each interval. It took me 1 minute and 30 seconds. It should be completely melted and smooth.
Stir in the vanilla and sugar, then stir in the soy milk until smooth.
Add the flour, baking powder and salt to the bowl with the chocolate mixture. Stir with a wooden spoon until just combined. Fold in extra chocolate chips, if desired.
Transfer the batter to the prepared pan, evenly.
Make the peanut butter swirl: In a medium bowl, stir together the peanut butter, melted vegan butter, powdered sugar and vanilla.
Drop spoonfuls of the peanut butter mixture on top of the brownies, then swirl it with a butter knife.
Bake for 35-40 minutes. For best results, let the brownies cool completely before cutting. You can stick them in the refrigerator to speed up the process. If you cut them immediately they will be very gooey in the middle, but if you let them cool they will be just perfect. Enjoy!