You’ll notice that when I talk about cooking, like here and here, I’m pretty vague about quantities, and sometimes about exactly what goes in — which herbs to use, what sort of cheese, that kind of thing. There’s a reason for that.
The reason is that for the sorts of things I’m talking about, I consider recipes to be starting points — inspiration, but not fixed rules. I tire of hearing people ask how much garlic they should put into something, or to say that they can’t make a certain dish because they lack some minor ingredient.
Part of the art — and the fun — of cooking is to try things, to experiment, to mix and match and mingle, and see what comes of it. You get to know what seasonings work together, what can substitute for what, and what, in fact, does have to be done in the right proportions (if you’re baking a cake, you need to be more particular than if you’re baking chicken).
You obviously can’t make my garlic/rosemary chicken without garlic, or rosemary, or chicken, but you know what?: you can make garlic/thyme chicken, or garlic/rosemary lamb chops, or....
And so you’ll never see me write an ingredient list that marks something as “optional”. They’re all optional. It really just there to give you the idea. You take it from there.