Everyone says to use a mixer for brownies, but I swear by a wooden spoon
Most bakers I know rely on their stand mixers for brownie batter to make it smooth. I did the same for years, but my brownies always turned out too cakey and dry. So I decided to stop using the mixer and just use a wooden spoon. I mix the ingredients by hand until they are just combined, even if the batter looks a bit lumpy. The first time I tried this, I was worried it would ruin the batch. But when I baked them, the brownies came out dense, fudgy, and had a perfect chewy texture. Now I never use a mixer for brownies, and everyone who tries them says they're the best. If you want richer brownies, give hand mixing a shot.
My hand mixer was the problem for ages. I’d beat the batter until it was shiny and smooth, and I’d get these dry, tall brownies every time. Switching to a wooden spoon and stopping while it still had some flour streaks made all the difference. They went from sad cake squares to that dense, sticky fudge texture I actually wanted.
Watch people murder their brownies with a mixer on high speed and wonder why they get dry cake squares. I had the same issue until I tried @valgibson's method and now my batter looks like a lumpy mess but bakes into perfect fudge. My stand mixer just gives me the side eye from the counter while I stir by hand. Guess it's back to being a very expensive whipped cream machine.