Preheat the oven to 350°F. Line an 8x8-inch baking pan with parchment paper.
In a large mixing bowl, add the canola oil, cane sugar, cocoa powder, and dark chocolate.
Pour the boiling water directly on top of the chocolate and mix with a hand mixer on low to medium speed until combined and the chocolate has completely melted and there are no chunks.
Add the egg, flour, ground vanilla bean, baking powder, and sea salt in that order. Mix on low until combined, do not over mix.
Add in half of the chopped peanut butter cups and stir to combine them completely. Transfer to the prepared pan and spread evenly. Add the remaining half of chopped peanut butter cups on top of the brownie batter.
Bake for 25 minutes to 30 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool completely in the baking pan.
Cut into 16 bars for mini brownies. Store in an airtight container for up to 5 days.