White sugar + foaming eggs = fudgy centers with classic glossy, crackly tops. The thicker your egg foam, the glossier/cracklier your top crust.
Brown butter deepens flavor and evaporates excess water in the butter. If you don’t want to brown the butter, melt it in a saucepan with the chopped chocolate, stirring until smooth. Pour over cocoa powder and espresso powder. Stir until smooth.
For extra thick brownies, use 8x8” pan. Bake time will be a bit longer.