This recipe makes a 9" x 13" pan full of crazy goodness, but if you don't trust yourself, it halves quite easily, in a 9" x 9" or 8" x 8" pan. It even quarters easily, in a loaf pan, but the brownies were harder to get out when I tried, so maybe that's best reserved for yoga-pant, errr... non-company nights.
They also freeze quite well! Wrap tight!