How long past the expiration date can you safely use cake and brownie mixes?

It's generally not recommended to use cake and brownie mixes past their expiration dates.

Here's why:

* Decreased quality: Over time, the ingredients in the mixes can degrade, leading to a less flavorful and less desirable texture.

* Potential for spoilage: Some ingredients, particularly leavening agents, may lose their potency and not work as intended, resulting in a flat cake or brownie.

* Safety concerns: While unlikely, there's a slight chance of bacterial growth in older mixes, especially if stored improperly.

However, there are a few things to consider:

* Check the ingredients: If the mix mainly contains dry ingredients like flour, sugar, and cocoa powder, it might be safe to use for a few months past the expiration date.

* Inspect the package: Look for signs of damage, moisture, or infestation. If the package is compromised, it's best to discard the mix.

* Smell test: If the mix has a strong, off-putting smell, it's a sign of spoilage and should be discarded.

As a general rule of thumb, it's best to use cake and brownie mixes within their expiration dates for optimal results and safety. If you're unsure, it's always better to err on the side of caution and use a fresh mix.