If you don't care too much, Onion salads are very easy to mass produce and offer both will+1/+2 (35% of total FEPS so a 1 in 3 chance of getting +1/2 if only eating these)
They also offer charisma, perception, and constitution which can all be useful enough. The downside is they have a relatively poor FEP/Hunger ratio.
https://certainly-not-a-cat.github.io/cookbook/ is a very good tool,
at the bottom you may type in "wil 40%-min" and it will show all the foods that give 40% or more of their total feps in will+1 or will+2
Oddly enough, stalagooms by themself have the 3rd highest FEP/Hunger ratio for will, second to strawberries in cream and the marshmallow autumn steak..
Onion Salad;
(Turnip, Leek);
Autumn Steak;
(Adder, Black Truffle, Marshmallow) |
(Adder, Black Truffle, Beetroot Leaf) |
(Adder, Black Truffle, Stinging Nettle);
Wonderful Wilderness Wurst;