Preheat your oven to 160C Fan / 180C and prepare a 9x9inch square tin with non-stick baking paper.
Melt together your butter and chocolate in a microwave (in short bursts, stirring regularly in between) or over a bain marie until completely melted. Mix together and leave out to cool down to just warm / room temp.
Sieve together your cocoa powder and flour in a bowl. Mix briefly until combined, put to one side.
In another bowl crack the eggs and pour in your caster sugar. Beat together (I use an electric hand whisk) until paler in colour and almost a little frothy.
Once the chocolate and butter mixture is cooled to room temp, pour it into your egg/sugar mixture. Fold it in with a spatula - it will initially marble and then turn super chocolatey.
Next fold in the your plain flour and cocoa powder mix. Ensure it's fully folded in.
Fold in your chocolate chips.
Pour/spoon your brownie mixture into your prepared tin and smooth it over so it's even and level.
Bake for about 35-40 minutes. The brownies will wobble slightly upon removing from the oven but will firm up as they cool. If you want them even more gooey, cook for 5 minutes less, if you want a firmer brownie, cook for slightly longer. I find with brownies all ovens seem to really vary.
Its really important to allow your brownies to cool completely before removing from the tin and slicing them. I find they firm up even more after slicing.
Once cool, slice your brownies into equal squares and then pipe or spoon the white chocolate across the brownies like in the pictures! Add the edible eyes (stick down with a dab of melted chocolate on the back of each eye) and allow the chocolate to set for at least an hour.