First post here, though I am an old fan of the game. If you read this toady, I love you!
There has always been a bit of an issue with cooking, the "dwarven wine biscuit situation". Every kind of food is classified the same, leading to dishes made out of just alcohol or just tallow.
My suggestion would be to put every foodstuff into one of three categories, similar to materials. These categories would be:
Standard, representing generally low-quality but high quantity foodstuffs. Examples would include plump helmets, flour and meat. These add their entire quantity to the produced meal.
Special, representing higher quality and stranger foodstuffs. Meant to represent things giving taste to the dis,h these would include some milled plants, rarer plants, tallow and possibly some kinds of rare meat. These add their entire quantity to the produced meal.
Spice, representing high quality foodstuffs that do not give actual substance to the meal. These would include alcohol, sugar, and milled spices. These add half of their quantity to the produced meal, but still all of their quality.
Every meal has to include at least one standard foodstuff, to avoid the dwarf wine biscuit situation. An example of how the kitchen menu could work:
Simple meal: One standard and one special OR spice
Standard meal: One standard, one special and one special OR spice
Lavish meal: Two standard, one special, one spice and one special OR spice
There could also be a custom meal, allowing you to create truly decadent feasts of up to five ingredients like honey roasted dragon roast in sauce of plump helmet wine and bulbroot powder.