Once captured, how does Bilbo try to bargain with the trolls?

Bilbo offers to cook the trolls breakfast if they agree not to eat him.

"What I say," said Bilbo gasping. "And please don't cook me, kind sirs! I am a good cook myself, and cook bet-ter than I cook, if you see what I mean. I'll cook beautifully for you, a perfectly beautiful breakfast for you, if only you won't have me for supper."