The most useful shape here is [X] 하면 빠질 수 없는 [Y] — 'the Y you simply can't leave out when it comes to X': 돈가스 하면 빠질 수 없는 우동 'the udon you can't have katsu without'. Note that 하면 there means 'when it comes to', not 'if you do'. On its own 빠지다 means dropping out or pulling out (쫄리면 빠져! 'if you're scared, fold!'), and also getting hooked: 먹다 보면 빠질 것 같기도 'I might get hooked the more I have of it'.