Preheat oven to 350℉. Line an 8x8 inch square brownie pan with parchment paper.
In a small pot, over low heat, melt together the chocolate chips and olive oil and set aside. In a large bowl, whisk together your eggs, sugar and vanilla. Mix in the cacao powder, arrowroot flour, espresso powder, baking powder and salt until incorporated. Then add in your melted chocolate mixture and stir until combined and smooth. Transfer the batter to the pan and smooth out the top evenly. Bake for 22-25 minutes or until toothpick comes out clean. Allow to set in pan for 15 minutes then carefully transfer to a wire rack to COOL COMPLETELY (at least 1-2 hours) before adding on frosting.
Mascarpone Frosting:
Beat the heavy cream and mascarpone until incorporated - about 30 seconds. Add in the powdered sugar and vanilla and beat for 1-2 minutes or until it thickens. Spread it out evenly onto the top of the brownie. Then, generously sift the top with cacao powder. Slice and serve.
Notes
Store leftovers in an airtight container in the fridge.
If you don't have mascarpone, you can use cream cheese instead.
Its very important that you allow the brownie to COOL COMPLETELY.