Translation:But that's absolutely the saucepan that I'm dreaming of!
I don't know about the use of the word 'absolument' in french it may well be used this way. However in English this sentence just doesn't sound right to my ears.
'Absolutely' usually means 'completely' or 'totally' but none of those sound right to me either.
I would never say this sentence in English, I would probably translate 'absolument' here as 'really' rather than 'absolutely'. 'But that's really the saucepan that I'm dreaming of' or 'But that's the saucepan that I'm really dreaming of' just sounds more natural.
Here in Canada, we use 'pot' meaning a cooking pot. I only see 'saucepan' in British cook books and at first think they mean 'frying pan', but then realize from context that they mean a 'pot'. "But it's absolutely the pot that I dream of!" was not accepted and I think the problem was the word 'pot' as 'it's' should be okay instead of 'that's'.
I'm aware that this site treats sentences that end with prepositions as normal. They still grate on this midwestern American's ear. Yes, Chicago Manual of Style says you can. Yes, my professors will call me on the practice. Yes, it's a practice from Romance languages, and French is one such language. We follow the practice of translating the concept as closely as possible to the original. That would mean that "But it is absolutely the casserole of which I dream" is the preferred translation. I would accept saucepan in place of casserole.
I don't think the English grammar of the close translation is so terrible. The problem is that the sentence is so strange a thing to say in English that it's hard to believe that it's actually saying what it does. "The saucepan of my dreams" is hard to imagine as anything other than a facetious remark. Could this be the case in French as well?