• Pre-heat your oven to 390℉/180℃. Line 12 muffin holes with cupcake/muffin liners.

First, Make the Brownie Batter:

• In a small bowl, break up the dark chocolate and melt in the microwave in 20 second intervals, stirring in between to make sure it doesn't burn. Alternatively, set up a double boiler. Do this by placing a heatproof bowl over a small pot of simmering water. Add the chocolate to the heatproof bowl and stir until melted.
• In a large mixing bowl, whisk together melted butter and both sugars. With an electric/stand mixer, go for a solid 3-5minutes so it is totally combined. Add in the eggs, one at a time and mixing in between. Add the chocolate slowly and whisk in.
• Add the salt, flour and cocoa powder, fold gently into the wet mixture with a rubber spatula or wooden spoon until just combined. Set aside.

For the Cookie Dough:

• In a large bowl, using an electric/stand mixer (or hand whisk, just double/triple the times) combine the butter and both sugars on medium speed for several minutes, until fully combined. Add the egg and vanilla and mix again.
• Add the flour, baking powder and chocolate chips and mix until combined.

Assemble:

• Scoop a large tablespoon - 2 tbsps of the brownie batter into each of the 12 lined muffin cups.
• I find using my hands is easiest for this: scatter the cookie dough on top. These don't rise very much so you can fill close to the top (leave 2-3cm). If you have any leftover cookie dough, see notes below!
• Bake 15-18 minutes, until the cookie dough is just golden on top. Remove and let cool before eating!