Cooking ingredients don't get unstacked in processing, the dwarfs really pick up a finished roast and slap some more ingredients into it.
Example from .34.11 (masterfully prepared sheep tallow roasts): excep. cave lobster (fem.), excep. cave lobster (male), masterful cave lobster (fem.), exceptional sheep cheese, excep. sheep tallow, excep. sheep tallow, excep. sheep tallow.
In .34, fat is unstacked in rendering, giving one-item stacks. So while there are only four distinguishable ingredients, it's also clear that even _if_ there was the possibility for ingredient-unstacking during cooking, at least six individual stacks of ingredients went into it. And there are no quarry bush leaves involved.
Another example, a five-ingredient roast: alpaca sweetbread, alpaca tallow, sheep cheese, alpaca lung, wolf meat; five ingredients, all different (no quarry bush leaves). PS: and there's the six-item stack of coyote tallow roast consisting of nothing but coyote tallow. In .34, this absolutely means six stacks of ingredients.
Quarry bush leaves _are_ particularly common ingredients in super-roasts: my reference fort has five overloaded "quarry bush leaves roast" stacks - 1x11, 1x7, 1x6 and 2x5 ingredients. The seven-item roast includes some guineahen eggs, the others are quarry bush all the way.