Preheat oven to 350°F. Line an 8x8 square pan with parchment paper and butter generously.
In a microwavable, melt butter and 3/4 cup chocolate chips until melted and smooth. Stir in 30 second intervals. Stir in sugar, vanilla and espresso.
In a small bowl, whisk the eggs until bubbly on top, about 1 minute. Add the eggs to the chocolate mixture.
In another small bowl, sift together the flour, cocoa powder, baking powder and salt. Add the dry ingredients to the wet ingredients and mix until just combined and then add the remaining chocolate chips.
Spread evenly into the pan and bake for 25-30 minutes. A cake tester should come up with a couple of crumbs. Let cool and then cut into 9 squares.
In a stand mixer fitted with a whisk attachment add the butter and sugar and mix on low-speed until blended and then increase speed to medium and beat for about 3 minutes..
Add vanilla and milk and continue to beat on medium speed for 1 more minute, adding more milk if needed for spreading consistency. Place in fridge until ready to use on brownies.
Pipe frosting over brownies in zigzag motion for mummy wrapping. Attach two eyeballs to each brownie.