Your grandmother cooks the way I do -- by instinct and experience. I have no recipes for such things as spagetti sauce (gravy), chili, lasagne, chicken soup or just about anything else I cook on a regular basis. You take basic ingredients and add spices and herbs based on past experience and instinct as to how much or whether a certain spice/herb will blend well with the other ingredients. Which is why I could never write down one of my recipes. It's never the same twice. LOL
It's also why I prefer cooking over baking. Baking is more of an exact science. Too much flour or baking soda and the whole thing is ruined. But have you ever eaten a spagetti sauce with too much garlic or oregeno?? I contend it can't be done! An experienced cook knows when to stop. Not enough? You can always add more. :)