A few a bits and pieces that may be of interest though I've not had the time to test in game.
The oven appears to use ingredients, first looking in the Sim's inventory then the nearest fridge, if not found it just buys them using the family funds (best guess at this time is it doesn't work this out to display on the pie menu and this is the only way you could fail to cook is if funds are less than the cost of recipe, the veggie trait may not be disabling the menu too). All easily tested in game.
Food quality is completely based on cooking skill (apart from a random chance of burning), level 9 and the meal is outstanding, oddly I can not see how a perfect meal could happen.
There is also a random chance you could fail to bake pizza.
I don't have the occult stuff but vampires may wish to avoid Calzone Alone and Bread Garlic, it also seems Vampires are the only occults that can get a buff from eating pizza.
Random stuffs:
There is a hidden Pizza Appreciator trait
There was going to be a Dessert Oven (or maybe I've missed it which is usually the case)
All recipes break down into bread, calzone, lasagna and pizza and then into normal, garlic, cheesy, meat, herb, sorpresa, pepperoni, loaded ^^ and lemon (also fruit but I think that's dessert); Cheesy Pizza is not cheesy but normal, go figure