Preheat oven for at least 10 minutes at 170C or 335F;
Grease with butter, then line both the sides and base of a 8"x8" baking tray with parchment paper;
Heat butter and chocolate chips in the microwave in 20 second bursts until melted, stirring in between, set aside;
In a separate bowl, use a hand beater with a double whisk attachment to beat the eggs, caster sugar, and brown sugar for 5-7 minutes until the mixture is fluffy and tripled in volume.
Add the melted butter, chocolate, coffee, and vanilla extract to the egg mixture, and mix well until combined.
Sift in the all-purpose flour and unsweetened cocoa powder, then add salt. Mix with a spatula until just combined, being careful not to overmix.
Add chocolate chips, mix till just combined.
Pour batter into prepared 8"x8" baking tray, spread out the batter evenly with an offset spatula. Sprinkle more chocolate chips on top (optional).
Bake conventional (top and bottom heating) at 170C / 335F for 22-28 minutes. Depending on how gooey and fudgy you want your brownie to be. Remove from oven according to your preference.
Allow to cool completely in the baking tray, remove from tray and cut to desired shape.
Decorate by drizzling over white chocolate and place two halloween/googly eyes to mimic an Egyptian mummy.
Ready to serve!