for the brownies:
for the frosting:
* Don’t beat the eggs and sugar quite as much as you would if you were making a sponge cake.
** If you’d like, you can make this without the cream cheese frosting. Simply decorate the brownies with the 2 tablespoons ground pistachios before baking, and skip the frosting.
*** You can make everything ahead up to this point, and then frost it later, a little while before serving (see notes on storage below)
Storage: These brownies hold pretty well in the refrigerator for a few hours, but longer than 12 and they will start to stale a bit (like many baked goods), so you should avoid refrigerating them by frosting them closer to the last minute. If you’re making them ahead for guests, you can bake the brownies ahead and keep them at room temperature for about 24 hours before losing any quality, or freeze the whole sheet of unfrosted brownies for up to 3 months (wrapped tightly) if you want to store them longer. You can also make the frosting ahead and keep it in the refrigerator for a few days. Bring the frosting to room temperature so it’s spreadable, and let the brownies thaw at room temperature (if you froze them), and then frost them at the last minute (or frost them a few hours ahead and store in the refrigerator). If you have any frosted leftovers, they freeze beautifully.