Preheat oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking pan.
Melt peanut butter, chocolate chips, and sugar together in a saucepan over low heat, stirring constantly, until chocolate is melted, about 5 minutes. Increase heat to medium and continue stirring until mixture begins to bubble, about 5 more minutes.
Remove from heat.
Blend avocado, soy milk, and canola oil in a food processor until smooth. Stir avocado mixture into chocolate mixture until thoroughly combined.
Whisk flour, baking powder, and salt together in a large bowl until well mixed.
Add avocado-chocolate mixture to the flour mixture; stir until just combined.
Pour batter evenly into the prepared baking pan.
Bake in the preheated oven until the edges begin to become crisp, about 20 minutes. Cool brownies completely before cutting and serving.
