Make your flax eggs by combining 280ml of boiling water with your ground flaxseed. Stir well and set aside for later.
Next, make your coffee mixture by combining a teaspoon of instant coffee and a teaspoon of boiling water. Stir well and set aside for later.
Sift together flour, salt, cocoa powder and baking powder in a large mixing bowl.
In a second mixing bowl whisk together oil, sugars and flax eggs until shiny and gloopy. You want the sugar to dissolve in the oil and flax egg.
Add the vanilla essence, coffee mixture and melted chocolate (dark and milk) to your oil mixture.
Combine the dry and wet mixtures to form your brownie batter. Stir until just combined and no flour can be seen. Do not overmix.
Pour your batter into a lined square baking tin. Use a silicone spatula to even out the top a little. Top with 4-5 heaped tablespoons of peanut butter, one in each corner and one in the middle.
To create the swirls, use a skewer to draw a pattern. Stick the skewer into the brownie mixture and drag through the peanut butter topping making a figure 8 movement from left to right.
Bake for 45-50 minutes at 180°C / 356°F (fan oven setting).
Always cool the brownie in the pan fully before cutting and serving.