Enriched dough help please!
Enriched doughs usually need either a whole lot of kneading or a whole lot of proofing time (or both - from memory Richard Bertinet kneads his brioche dough for about 10 minutes then proofs for 14 hours). 

One other trick is to add the butter after initial kneading so that you can form some gluten first. This should make the resulting bread less 'cakey'.