I'm glad to know you've found Muffin something that's restored her normal eating behavior.
If you get the urge to cook for her sometime, your vet can give you recipes that are appropriate, especially for dogs who are senior or have any health concerns. I would not give any dog a recipe found on the Internet because despite claims to the contrary, they may not be based on medical knowledge about what dogs need, and they are definitely not tailored to the needs of your particular dog. There are a lot of kindhearted people who mean well but don't know what they're doing.
Just recently our vet recommended a kidney diet canned food for dogs for our 15-yr-old dog. We have had a previous dog with this condition and he would eat this particular food at all, which was very frustrating because it's expensive. This time I told the vet that I didn't think Rascal would eat it because his appetite has been very poor, and she gave me several recipes that I can easily cook for him. I make big batches and freeze the extra until he's ready for it. I found that giving him food made with fresh ingredients is actually less costly than the other stuff, and he really appreciates it. We were worried because he was underweight and often did not want to eat. I'm happy to say that he has been eating home cooking for about a month and is doing much better than he was.
I think the major pet food companies do considerable research on ways to meet a dogs needs while maximizing their profits. The two objectives are inherently somewhat at odds with each other, and what might be okay for the average young, healthy dog would not necessarily be ideal for one that is past his prime or one that is very active or inactive.
Best wishes for you precious fur baby.