Cookie dough can be frozen, so you might want to try freezing brownie batter, as well. The problem is that brownie dough is thinner than cookie dough -- somewhere between cake batter and cookie dough. It's impossible to form into balls or rolls and some of its ingredients may not freeze well. In general, it's best to bake the brownies before freezing them.
Freezing is an excellent way to preserve almost any food for longer storage. Although brownie mix lasts for a long time on the shelf, freezing it extends its life, especially if you live in a hot, humid climate, where stored foods deteriorate more quickly. Freeze the brownie mix in its original box and date the box. Use it within two years.
Once you add water, eggs and oil to a brownie mix, it should not be frozen. When raw eggs are frozen and then thawed, they may become rubbery or watery. Additionally, if the brownie mix has any baking powder in it, it should be baked immediately after mixing. If you freeze the batter, the leavening agents might not work when you thaw them, resulting in a hard, dense brownie.
One option is to bake the brownies, cool them and cut them in squares. Place the brownies in an air-tight plastic bag or box and place a sheet of parchment paper between each layer. Seal the box or bag and freeze the brownies for up to three months. Thaw them on the counter before serving. Brownies frozen this way will taste fresh and moist when thawed.
You can dress up frozen, baked brownies after they've thawed. Melt whipping cream and chocolate together to make a thick ganache frosting or drizzle brownies with melted white chocolate. When baking brownies, use the correct pan and watch the brownies closely. Overcooking them causes dry, tough brownies. They're done when a knife inserted in the middle comes out with only a few fudgy crumbs. One trick for perfect brownies is to line the pan with parchment paper. Grease the parchment paper and cook the brownies. Once the brownies are done, let them cool in the pan for a few minutes and then turn them out onto a cooling rack. Once they're completely cool, cut them into 2-inch bars.