Cooking oil or butter.
The same amount of butter as oil. You may have to melt it if it was a fluid measurement.
Assuming this is a recipe that uses just oil and no butter or other fats and you are not planning on replacing the oil with some other fat then it will be dry.
A brownie requires chocolate-like substances, along with multiple other ingredients. If you only used peanut butter, it wouldn't be a brownie, but more of a peanut butter sculpture in the shape of a brownie. I don't think you can make a brownie out of just peanut butter but im sure you could put peanut butter chips into it and make it be chocolate and peanut butter! That sounds good!
Chocolate and butter!
In certain recipes yes, though I personally think the flavor is compromised when substituting oil for butter (haven't found an oil based brownie I liked better then a butter based). Your best bet it is to find a brownie recipe that specifically uses oil instead of butter for optimal results. As a general rule substitute 3 parts oil for every 4 parts butter and consider increasing the amount of sugar and eggs in the recipe to help make up for the increased density. But again I would recommend using an already oil based brownie recipe. But yes it is possible.
You should use the same amount of butter. It's probably also best to melt the butter so that it combines well.
The answer is 12.5 pounds of butter.
Peanut butter is not an oil, but it does contain oil. It contains peanut oil, of course.
It is so called because there is an explosion of tasty ingredients. Apart from peanut butter, it contains fudge brownie, peanut butter mousse, fudge and peanut butter chips.
Use butter. But isn't butter the same as oil?
There is no sunflower oil in butter.