Fudgy or cakey is not a matter of taste, it is a matter of technique. The same ingredients produce either one depending on how much air you put in, how long you mix at the end, and when you take the tray out.
This version comes from Cakes by MK, who went through a long stretch of testing to work out the shiny crinkle top specifically. Three things produce it, and none of them are obvious.
Where the crinkle top comes from
That thin, glossy, papery layer is dissolved sugar rising to the surface and setting as the brownie bakes. You get it by doing two things.
Melt some of the sugar into the hot butter and cocoa mixture rather than adding all of it dry. And whip the eggs with the remaining sugar for a full three minutes until pale and creamy, which dissolves the crystals and carries air to the top.
Skip either and the brownies still taste good. They just come out matte.
Bloom the cocoa
The butter, oil, cocoa and brown sugar go into the microwave together and come out genuinely hot to the touch, not just melted.
Heat is what unlocks cocoa powder. Stirred into a cold batter it stays flat and slightly chalky; heated in fat it turns deep and properly chocolatey. That is the same reason there is a teaspoon of coffee powder in here - it is not there to taste of coffee, it is there to make the chocolate taste more like chocolate.
Butter and oil, not just butter
Butter brings flavour, oil brings the fudgy texture that stays soft once it cools. All butter gives you a firmer brownie straight from the fridge. The combination keeps it dense and yielding.
Stop mixing
Once the flour goes in, fold gently and stop the moment it disappears. Every extra pass develops gluten, and gluten is exactly what turns a fudgy brownie into a cakey one.
The same caution applies when the chocolate mixture goes into the whipped eggs. You spent three minutes putting air in there. Stirring hard takes it straight back out.
Underbake them on purpose
This is the single biggest lever. 22 minutes for properly fudgy, 25 for something closer to a set cake, and the difference between the two really is that narrow.
A toothpick should come out dirty, with moist crumb clinging to it. If it comes out clean they are already overbaked, and they carry on cooking in the hot tin after you pull them.
Let them cool completely
An hour in the tin, no shortcuts. Warm brownies have not set and will tear rather than slice.
Line the tin with baking paper so you can lift the whole slab out in one piece, then cut on a board with a long knife, wiping it between cuts.
Chocolate choice
Use 50% dark or semi-sweet, chopped into large chunks rather than chips. There is a lot of sugar in this recipe and dark chocolate is what stops it tipping into sickly. The chunks also stay as pockets rather than melting away into the crumb.
More baking from scratch
If this one worked out, these run on the same ideas: