Preheat oven to 180° and pop some parchment paper in a deep tray
Melt your chocolate and butter, the best way to do this and keep it creamy is via putting a heatproof bowl on top of a pan of boiling water. Once these are both melted together give it a good stir and set to one side.
In a separate bowl add sugar, cocoa powder, flour and eggs then mix them together.
Once cool slowly start adding your chocolate and butter mixture to the pan where the other ingredients are. You will need to blend this well if you have a good processor this may be your best option as the mixture is thick.
Smash up some of the mini eggs and smarties. Do this in a zip lock bag as it allows you to apply force and make less of a mess. You want to create lots of bits to spread throughout your brownie.
Tip into the tray which you prepped earlier then place some more mini eggs within your mixture. Use a knife to push some further into the brownies as well. Then pop in the oven to cook for 15 minutes.
Take the brownies out of the oven and add even more eggs/smarties and then pop in for 10 minutes.
Let it cool and then cut into 12.