We are having battles with 3yr old DS. If he had his way it would be sausages, sauce and bread every meal - he wont eat chips thank god!
Tonight was pork steaks, roast pots, peas and sweetcorn. We didnt give him the pork as he struggles to chew it so spits it out, but he had 3 roast potatoes, peas and sweetcorn with gravy.
Pushed it away, i mashed the potatoes up with the peas and sweetcorn and gravy, and he has (after sitting under the table for a few minutes) eaten the whole lot, and is now having a slice of bread (at his request) before yoghurt for pudding.
Its a battle ground, but as long as they have made a good attempt at the meal, Im happy.
DD1 (6yrs) is very fussy with vegetables, but she knows she has to have at least 1 on her plate and eat it, and she does through gritted teeth!
DD2 is a pig and will eat anything except fish, chips and melon!
With regards to your DD, I would be happy with her having eaten the cottage pie, and wouldnt push the veg too much.
DS is still only 2, and I found with my Ds especially, he didnt really start eating "meals" properly until nearer 3. I would offer "finger foods" again for a bit to get him back into the swing of meal times.