In a pudding I eat,
I give bread its potential,
In a trial I'm neat,
But in math I'm essential.
What am I?
You are
PROOF.
In a pudding I eat
I give bread its potential
Proofing is a step in the process of breadmaking which allows the bread to rise to its full potential.
In a trial I'm neat
It's good to find proof of guilt or innocence in a trial.
But in math I'm essential.
Proofs are certainly essential in maths!