How do you tell someone that they're a terrible cook?

Especially since she does it for a living. (Note. I would never & will never tell her that.)

Some lady bought a grocery store in this tiny town.
To supplement her meager income she cooks, and sells, homemade food. Without exception the food is awful!
One day she made corn bread and ham and beans. The corn bread was good, but the beans and ham were in water. Just…water. It’s like she hadn’t boiled them down at all.
This morning I wanted cinnamon rolls so he ran to the store to get a can.
They didn’t have any. However she did have a pan of homemade cinnamon rolls.
I took one bite and just gagged. It’s like she put some random flavoring in it (imagine garlic or something that does NOT belong in a cinnamon roll) and very little cinnamon and sugar. The icing was like she put powdered sugar in water and mixed it up. No vanilla, nothing. I couldn’t eat it and I’m hungry!

It’s all uniformly bad so I’ll quit buying her $5.00 lunches.