I'm going to ignore my mom when she asks if she can have some of the food we're cooking.
What good will ignoring your mom do when she asks you for some food?
The food is for friends and I'm not planning on sharing it with her.
Don't just ignore her, that's rude. You should be happy to share the food, especially with your mom. Give your mom some of the food, it's good to be nice to family members.
I'm assuming that you are also a parent.
It would just be nicer if you answered your mom. I think she would probably understand if you told her you wanted to save it for friends. What would be even nicer is if you made something for her as well.