Line a muffin tin with liners. You'll make between 12-18 depending on how thick your brownie mix is. The mix in the picture made 12, the next time I used a different mix (both said for an 8x8 pan) and I got 18.
After they're done, take them out and let them cool. If you're planning on eating one right away, don't let it cool down much - just enough to keep from burning your fingers. They taste great covered in vanilla ice cream and hot fudge - trust me :)