At every stage he escalated.
Potential 'crime' by OP: thinking aloud about getting herself a takeaway and didn't immediately offer getting him some, taking a few seconds to do so.
He could have waited for her to offer, asked for some or said he'd grab himself something different. Instead he had a go at her, called her selfish and guilt tripped her.
He could have then apologised for reacting badly and either accepted the further offer for food or made/ordered himself something. Instead he insulted her further and dismissed her offer as 'pity food'.
He then could have made himself something easy that takes 10 mins and had his sulk. Instead he ate his baby's food, wasting OPs efforts and upsetting her. He guilt trips her as he does this by saying its pathetic he was 'forced' to eat pastries for dinner.
He could have apologised when OP got home or simply sulked by himself. Instead he attempted to deflect then had a tantrum and stormed upstairs.
He could have stayed up there to calm down but instead he came down, accused OP of not talking to him 'over pastries', threatened to walk out then got angry when OP didn't beg him not to.
At every possible stage, he has picked the action that caused and worsened the row. Over ABSOLUTELY NOTHING!